Legionella Control in Healthcare

7/30/2019 Legionella Control in Healthcare

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An engineering approach to legionella control in Health Care Facilities

ContentsAbstract ................................................................................................................................................... 3

1. Introduction..................................................................................................................................... 4

2. Legionella. .......................................................................................................................................... 5

2.1 What is legionella?........................................................................................................................ 5

2.2 What is Legionellosis? .................................................................................................................. 7

2.3 Legionellosis in Hospitals. ............................................................................................................ 9

3. Legislation......................................................................................................................................... 10

3.1 Irish legislation............................................................................................................................ 10

3.2 Special provisions for Hospitals. ................................................................................................ 12

4. Legionella Control ............................................................................................................................. 13

4.1 The Building services engineers role......................................................................................... 13

4.2 Engineering Control Methods ..................................................................................................... 14

4.2.1 Design and Installation of water storage systems-hot/cold .................................................. 14

4.2.2 Design and installation of water delivery systems-hot/cold................................................. 18

5. Maintenance of water storage and delivery systems......................................................................... 20

5.1 Cold water storage tank cleaning ................................................................................................ 20

5.2 Hot water calorifier cleaning....................................................................................................... 22

5.3 Chlorine dioxide treatment.......................................................................................................... 23

5.4 Automatic flushing systems ........................................................................................................ 27

5.5 TMV and showerhead cleaning .................................................................................................. 30

6. Testing and record keeping ............................................................................................................... 31

6.1 Quarterly water testing................................................................................................................ 31

6.2 Daily chlorine dioxide readings .................................................................................................. 34

6.3 Monthly hot/cold water temperature testing ............................................................................... 367. Interaction with other stakeholders ................................................................................................... 37


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7.1 Medical staff education ............................................................................................................... 37

7.2 Household/Catering staff flushing regimes................................................................................. 38

7.3 Circulation of information/test results ........................................................................................ 40

8. Case studies....................................................................................................................................... 41

8.1Basildon University Hospital ....................................................................................................... 42

8.2 St Patricks University Hospital.................................................................................................. 45

9. Conclusions....................................................................................................................................... 53

10. Bibliography ................................................................................................................................... 55

11. Appendices...................................................................................................................................... 56

Appendix A ........................................................................................................................................ 57

Appendix B ........................................................................................................................................ 59

Appendix C ........................................................................................................................................ 61

Appendix D ........................................................................................................................................ 63

Appendix E ........................................................................................................................................ 65

Appendix F ........................................................................................................................................ 67

12. Acknowledgements......................................................................................................................... 72


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AbstractThe purpose of this dissertation is to examine the legionella bacteria and its

implications for the Health care sector from a building services engineering perspective. The

role of the building services engineer is crucial in the control of legionella as the engineer is

involved from the initial stages of designing the water systems for a new building. Thebuilding services engineer may also be responsible for the on-going maintenance of the water

storage and delivery systems in the role of Facilities Manager.

Currently, legislation aimed at controlling the legionella bacteria is in place in Ireland and

special precautions must be taken in Hospitals and other Health Care facilities. I will examine

a Hospital in Ireland that has implemented a stringent legionella control programme and see

what effect such a programme can have on the incidence of high legionella bacteria counts.

Neither of the two Hospitals I have chosen for my case studies employ cooling towers as part

of their ventilation process so I will concentrate more on the risks associated with the hot and

cold water delivery systems as this area is now recognised to be particularly important from a

legionella control point of view.

Having examined the various control methods available, I will be able to draw conclusions as

to their effectiveness and whether or not more needs to be done from both a legislative and

practical point of view to control the legionella bacteria.


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1.Introduction.The legionella bacteria poses a significant threat to the health of Patients in the Irish health

system today. This threat is not as obvious and has not had as much media exposure as other

risks to hospital in-patients such as MRSA or the winter vomiting bug. Legionella is an

invisible threat and the symptoms of legionellosis are not immediately attributable to thelegionella bacteria. Left unchecked and allowed to flourish in favourable conditions, the

legionella bacteria can multiply with alarming speed to a point where it poses a real threat to

patient health. Because it is a water borne bacteria it can quickly infect an entire hospital

complex as it spreads through the hot and cold water supply.

The role of the Building Services Engineer is crucial in combatting the prevalence and spread

of the bacteria. Proper design and maintenance of the hot and cold water storage and delivery

systems is essential. Engagement of external expertise in the form of a full risk assessment

for legionella allows the engineer to structure a strategy for controlling the bacteria rather

than adopting a piecemeal approach. Interaction between the Building Services Engineer and

all the other professionals and stakeholders in the Hospital is essential as any legionella

prevention programme must involve full participation by all parties from the Medical staff

through to the Household and Maintenance employees. Circulation of information, test

results, prevention initiatives, etc. are all important in ensuring that everyone concerned buys

into the message that legionella is an ever present threat in our Hospitals which cannot andmust not be taken lightly.

An examination of the legionella control methods currently being implemented by a Hospital

here in Ireland and contrasting that with another health care facility which lacked a legionella

control programme and subsequently suffered an outbreak of legionellosis will crystallise and

clarify both the importance of a stringent legionella control programme and the key role that

the Building Services Engineer plays in it.


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2. Legionella.

2.1 What is legionella?

Legionella is an aerobic bacterium, usually sausage shaped and between 1 and 2 m in

diameter with a thin flagellum or tail-like structure that it uses for propulsion. Compare this

to the diameter of a human hair at approx 100 microns.

Human hair 1x10 m Legionella bacteria 1x10 m

The legionella bacteria was named following investigations into a mystery illness that struck

delegates to the annual convention of the Pennsylvania American Legion at the Bellevue

Stratford Hotel in 1976. Thirty four delegates succumbed to pneumonia like symptoms and

died while over two hundred fell ill but later recovered. The legionella bacteria was

eventually isolated and recognised mainly due to the work of Dr. Joseph McDade from the

U.S. Centre for Disease Control. Because it was a newly discovered bacteria the illness

associated with it was named Legionnaires disease after the first known outbreak and the

bacteria was named Legionella.
http://www.wrongdiagnosis.com/phil/html/legionnaires-disease/2015.html


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Although the exact source of the Pennsylvania outbreak was not found it is now known that

the legionella bacteria thrives in water and survives and multiplies at water temperatures

between 25 and 50C with at optimum temperature of around 35C. Temperatures below

20C inhibit the growth of the bacteria and it is quickly killed at water temperatures over

60C. It can be seen from the table below that optimum conditions for the growth and spread

of the legionella bacteria occur in processes such as spray humidification, cooling toweroperation and domestic hot water applications such as shower facilities. Steam humidification

and low temperature hot water radiators use water at temperatures too high for legionella to

survive while drinking water supplies and AHU cooling coils operate at lower water

temperatures than those favoured by the bacteria.


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2.2 What is Legionellosis?

Legionellosis is a respiratory illness in people caused by the legionella bacteria. There are

many strains of legionella but the one most often associated with legionellosis is legionella

pneumophila. For an individual to contract legionellosis from a water source, four factors

must be present. These are

1. Multiplication of the legionella bacteria in the water to a level where it cancause infection

2. Creation of an aerosol containing the legionella3. Inhalation of the aerosol by an individual4. Susceptibility of the individual to infection

1. Legionella can and should be assumed to be present to some degree in all water systems.Under favourable conditions the bacteria can multiply to dangerous levels in as little as

seven days. The exact dose of legionella necessary to cause illness in humans is not

known but present guidelines set 1000 coliform units as the level at which remedial action

must be taken if the bacteria is detected. As seen earlier water temperature plays an

important role in the bacterias ability to thrive but another important feature is the

presence of biofilm in the water storage and distribution systems. Biofilm is visible to the

eye and is the slimy substance found on the inner surface of distribution pipework. It is

made up of naturally occurring amoebae and protozoa in the water. The legionella

bacteria is a parasite of these organisms and can survive inside them even when othernutrients are in short supply. The legionella bacteria is also less susceptible to water

treatments involving the use of free chlorine whilst sheltering within this biofilm. Other

sources of nutrient for the legionella bacteria can come from poorly maintained and

uncovered water storage tanks, poor hygiene standards during installation or remedial

works on water distribution pipework and use of nutrient rich plumbing products such as

certain pipe jointing compounds and hemp.


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2. If the biofilm in the water supply network is infected with legionella and it becomesdislodged for any reason, this can lead to a rapid release of large amounts of infectious

bacteria. Possible causes of such dislodgement would include local repair or expansion

works which necessitate the breaking of pipework joints and not flushing new

installations thoroughly before initial use. If this release of bacteria coincides with the

formation of a water aerosol at the delivery point then the possibility for human infectionexists. Aerosol formation may take place in cooling towers, showering facilities

connected to hot and cold water supplies, decorative fountains and spas to name just a

few.

3. For the legionella bacteria to cause legionellosis in humans it must gain access to thelungs. This is the only route that will cause infection. Consuming water does not cause

legionellosis and there is no evidence of person to person contamination.

4. The incidence and severity of infection depends on the susceptibility of the individual andtheir overall health condition. Permanent reduced lung capacity may occur following

infection. The following people are thought to be at higher than average risk of

contracting legionellosis

Older peopleover age 40- Males People who smoke People who drink to excess People with suppressed immune systems. For example HIV sufferers or organ

transplant recipients

People with underlying health problems such as diabetes, heart complaints andrespiratory problems. It is thought that stroke sufferers and people with

alcohol addictions are at greater than normal risk as their choking reflex may

not be functioning properly and this may allow swallowed liquid containing

traces of legionella to be aspirated into the lungs.


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2.3 Legionellosis in Hospitals.

Hospital Management has an important role to play in implementing and prioritising any

legionella control programme. The duty of care that exists in a hospital situation differs

from a hotel or guesthouse in that the hospital patient is normally already vulnerable to

infection due to medication or a suppressed immune system. In a psychiatric hospital patients

may have the added risk of being prone to self-harming. There is a risk of self-inflicted scald

injuries in such instances if patients are allowed to regulate their own shower water

temperatures. Strong medication such as anti-depressants may lead to patients becoming

immunocompromised and more open to legionella infection.

Hospitals by their nature tend to be large buildings or a collection of buildings and will

probably have extensive and isolated water storage facilities. Cold water storage tanks may or

may not be designed and installed to modern standards. There may be several plant rooms on

site supplying domestic hot water to different buildings. Hot and cold water delivery

pipework will tend to be very extensive, may or may not be properly insulated throughout its

length and may or may not be properly marked on layout drawings. All of these factors need

to be taken into account by the building services engineer at the initial planning stages for a

new building and when planning a legionella control programme for an existing building or

complex.


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3. Legislation

3.1 Irish legislation.

The main legislative provisions in relation to the control and prevention of legionella

infection in Ireland are found in Health and Safety at Work legislation and some are modelled

on existing British legislation. The relevant acts are

The Safety, Health and Welfare at Work Act 2005 The Safety, Health and Welfare at Work ( General Application ) Regulations

2007

The Safety, Health and Welfare at Work ( Biological Agents ) Regulations1994, amended in 1998

The Safety, Health and Welfare at Work ( Chemical Agents ) Regulations2001

The Infectious Diseases Regulations 1981 The UK Health and Safety Commission (HSC) document, Legionnaires

DiseaseThe control of legionella bacteria in water systems - Approved Code

of Practice L8;

The Health Protection Surveillance Centre (HPSC) - The Management oflegionnaires disease in Ireland (Endorsing HSC Approved Code of Practice);

Health Technical Memorandum 04 01 Water Systems: The control ofLegionella, hygiene, safe hot water, cold water and drinking water systems.

Part A Design, Installation & testing;

Health Technical Memorandum 04 01 Water Systems: The control ofLegionella, hygiene, safe hot water, cold water and drinking water systems.

Part B Operational Management.


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The 2005 Act applies to employers, employees and the self-employed and sets out the general

guidelines for managing risks. Section 19 of the act requires the employer or any person

responsible for the safety of the workplace to carry out a risk assessment. The risk assessment

relates to employees and people not employed but availing of the buildings facilities, for

example hospital patients. A safety statement must be prepared setting out how any risks are

managed.

Section 16 of the 2005 Act states that designers, manufacturers and suppliers of articles have

a duty of care to ensure that plant and machinery is free from risk to health when used

properly. This means that the building services engineer must ensure that the design of the

hot and cold water systems in a building is to a standard that will not promote the growth of

harmful bacteria such as legionella.

Under the 1994 ( Biological Agents ) regulations legionella pneumophila is listed as a group

2 biological agent. This means that it is capable ofcausing disease in humans but is unlikely

to spread to the wider community and is treatable with antibiotics. Regulation 3f of the act

deals with situations where it is not intended for a person to intentionally come into contact

with a biological agent but where such contact may occur during cleaning and maintenance

operations. This would be the case when facilities personnel undertake cleaning of existing

water distribution systems.

The 2001 ( Chemical Agents ) Regulations pertain to legionella insofar as they set out the

standards required when using chemicals such as biocides and disinfectants to clean water

storage and delivery systems.

Under the 1981 Infectious diseases regulations, legionellosis is a statutorily notifiable disease

and any suspected cases must be made known to the local health authority .Suspect cases

must be investigated and any remedial works necessary to remove the source of the infection

carried out.


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The National Guidelines for the Control of Legionellosis in Ireland 2009 sets out the most

up to date guidelines available for the monitoring, prevention and control of legionella in this

country. It sets out best practice guidelines for carrying out risk assessments for legionella,

for designing and maintaining water storage and delivery systems and for record keeping and

legionella testing regimens. It also recommends that the Irish Government introduce

legionella specific legislation without delay concerning

1. Maintenance and disinfection of any equipment capable of producing anaerosol contaminated with legionella

2. Statutory notification by owners of high risk sites such as cooling towers3. The setting up of a statutory authority for the monitoring of these and other

high risk sites

3.2 Special provisions for Hospitals.

The National Guidelines for the Control of Legionella in Ireland 2009 sets out the

legionella control measures to be undertaken in Hospitals based on the legionella policies and

procedure of the HSE South Eastern health Authority. Under these guidelines the Manager or

Chief Executive Officer of the Hospital is responsible for the appointment of a nominated

responsible person who is tasked and adequately resourced to carry out duties relating to

legionella control. It recommends the setting up of an Environmental Monitoring Committee

for each Health Authority area. At local Hospital level this could be an Infection Control

Committee. It recommends that a building services engineer or equivalent be a member of

that committee and fulfil the following roles.

Ensure new heating and ventilation systems are designed to the correct standards Carry out a risk assessment of the water storage and delivery systems Ensure any system modifications and works are carried out in accordance with best

practice guidelines

Ensure all routine system inspections, maintenance and disinfections are carried out ina timely manner


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Delegate water testing and temperature monitoring to relevant personnel Disseminate legionella test results and other relevant information to other

stakeholders

Ensure all records are properly kept, regularly updated and available for inspection onrequest

4. Legionella Control

4.1 The Building services engineers role

The building services engineer can and must play a central role in controlling the legionella

bacteria in hospitals and other health care facilities. Proper planning of the water storage and

delivery systems at the design stage will minimise the risk of legionella colonisation at a later

stage and lessen the need for costly remedial work and high on-going maintenance charges.

The engineer must understand where the main legionella risks occur in hot and cold water

systems and then try to design out as many of these risks as possible. Examples of avoidable

risks could include long runs of poorly insulated cold water delivery pipework through heated

voids where temperature gain in the cold pipe becomes inevitable. Also wrongly sized

calorifiers may mean the target temperature of 60C may not be realised because of heavy

load resulting from poor planning at the design stage. An understanding by the design

engineer of the building management system chosen at the design stage of a building and the

applications of the BMS to legionella prevention is very important. The BMS can be

invaluable for automatic monitoring of calorifier flow and return temperatures, automatic

temperature monitoring at cold water storage facilities and automatic monitoring of chlorine

dioxide dosing systems. Temperatures outside design parameters can be quickly sensed and

alarmed by the BMS allowing the operator to take any necessary remedial action at an early

stage.

In the role of Facilities Manager, the building services engineer plays a pivotal role in

ensuring the on-going maintenance and monitoring of the various components that make up


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the hot and cold water supply system. The engineer must ensure that any works which

involve breaking into the hot or cold water supply are carried out to standard so that

pollutants are not introduced into the system. Breaking the supply pipework in an already

infected system can lead to massive amounts of the legionella bacteria being released into the

water flow and possibly to outlets being used by already vulnerable hospital patients. The

engineer fulfilling the role of Facilities Manager is responsible for ensuring that all systemmaintenance and disinfection is carried out in a timely manner and that all records are

properly filed and available for inspection by relevant authorities.

Of all the health care professionals involved in ensuring that the legionella bacteria remains a

diminished threat, it is the building services engineer who has the most influence because

through his understanding of the bacterias requirements for growth, the engineer can break

the chain of infection and directly minimise the risk to patients.

4.2 Engineering Control Methods

4.2.1 Design and Installation of water storage systems-hot/cold

The design stage of the water storage system is crucial in minimising the risks from

legionella. If the proper precautions are not designed in at this stage the storage systems may

become breeding grounds for the bacteria which can then spread through the delivery pipe

network. The initial sizing of the cold water storage tank is important but not easy as it will

be based on forecast use and projected patient and staff numbers which may or may not be

realised in reality. Therefore the initial sizing should take this into account and make

allowance for possible future alterations to the stored volume. This can be achieved through

the use of variable volume supply valves which can increase or decrease the volume of water

stored without the need to physically adjust the supply ball valve. It is important that no more

than the 24 hours of water storage capacity recommended is provided for as water which is

allowed to remain in the storage tank for longer than this is prone to increased temperature.

This may not seem to be a problem on a cold day in January but in mid-summer and bearing

in mind that the water will inevitably gain even more in temperature as it travels through the


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delivery pipework, this can be the difference between maintaining the cold supply below the

necessary 20C at the outlet or not. Adequate insulation and a tight fitting and insulated

hinged access cover are necessary to protect the cold water storage tank from excesses of heat

and cold. Light must not be allowed to penetrate the tank as this encourages the growth of

algae which will provide a nutrient base for the legionella bacteria.

The positioning of the inlet and outlet pipes also plays an important role in water storage tank

design. The inlet and outlet must not be positioned on the same side of the storage tank as this

can lead to short circuiting of the water and insufficient mixing of the water within the tank. I

have taken temperatures from a storage tank wrongly plumbed in this way and found a swing

of more than 1C across a relatively small tank containing 7,500 litres. The negative effects

of such short circuiting are even more obvious in interconnected tanks. In this situation the

unplumbed tank will effectively have little or no turnover of water except in periods of very

high usage. If allowed to stagnate for long periods this water is likely to become increasinglycolonised by legionella which may be drawn into the supply network during heavy use

Mains water

supply

Insulation

all around

tank

Typical Cold Water

Storage Tank

Alternative

Cold WaterService (CWS)

outlet

Cold Water Service

(CWS)

Lid

Screened

vent

Screened

overflow

Air gap to meet water

regulations

Drain


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periods if the plumbed tank cannot meet the demand. Interconnected cold water storage tanks

should be individually served by separate supply valves and the outlet from each tank should

be positioned as far from the inlet pipe as possible.

The picture above is of the interior of a very small water storage tank of just 2,500 litres. The

inlet to the tank is at the right side of the photo and the outlet is at the top of the photo. The

distribution of the grit at the bottom of the tank shows very clearly that the water is taking the

shortest route between the inlet and outlet and the water at the bottom and left sides of the

photo is stagnating. Imagine how much this undesirable situation would be magnified in a

wrongly plumbed storage tank of 20,000 litres which is not an uncommon size for a cold

water storage tank in a large facility


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The sizing of the hot water calorifiers is critical in maintaining the proper temperature within

the vessel during all load periods. Again this sizing will be based on projected use if the

calorifier is being designed for a new building and once installed it will be very costly and

labour intensive to replace it later so accurate sizing is important. Calorifiers are naturally

cooler at the cold water inlet level and this lower level is also the area most likely to have

accumulations of debris and sludge. This area of the calorifier is more susceptible tolegionella contamination than the hotter upper strata. If the calorifier is undersized, water

from this lower infected area of the calorifier may be drawn into the system pipework during

high use periods. Modern sizing methods allow for generous margins and there is little

danger of under sizing of new installations but care must be taken when planning to increase

the load on older calorifiers to serve a new hospital wing for example. There are two ways to

overcome the problem of reduced temperature near the calorifier base. A circulating pump

can be fitted within the calorifier to mix the water to a uniform temperature. However this

approach disrupts the water stratification within the vessel and so can only be undertaken

when the calorifier is not discharging. This approach is not very practical in a busy hospital

with 24 hour operation. A more realistic approach is to ensure the maximum possible

insulation is applied to the base of the calorifier and the addition of localised electrical trace

heating should be considered. If a legionella outbreak occurs in a hospital, one of the quickest

remedies available is to thermally treat the entire hot water storage and delivery systems. This

involves raising the calorifier temperature to 80C and passing this superheated water

through the delivery pipework for one hour under controlled conditions. The calorifier must

be designed to be capable of reaching and maintaining this raised temperature if necessary.

Finally all calorifiers should have drain points fitted at the base to allow for cleaning and the

taking of samples for legionella testing.


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4.2.2 Design and installation of water delivery systems-hot/cold

Successfully minimising legionella colonisation of the hot and cold water delivery pipework

begins with implementing good mechanical design and installation practices to include the

following

Sediment traps at the bottom of long vertical runs of pipework and flushing points onlong horizontal pipe runs to allow periodic purging of the lines

Use valves that do not encourage the build-up of sediment and other trapped objects atthe valves themselves. Globe and gate valves will allow a certain amount of debris to

accumulate and this could be a nutrient source for bacteria. Ball valves in the fully

open position will not trap debris and should be favoured

Globe valve Gate valve Ball valve

Smaller diameter tap offs from main pipes should be taken from the top half of thepipe so as to minimise the risk of creating a debris trap at the branch. All pipe burrs

should be removed for the same reason.

Hot and cold pipe runs must be properly insulated with the recommended thickness ofinsulation material. When installed in close proximity to each other, the hot pipe

should be above the cold so as to minimise any possible heat transfer.

It is good practice to finish a pipe run at a frequently used outlet such as a wc toensure regular flushing of the entire pipe length
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Pipe runs should be reviewed regularly to ensure that no dead legs have been createddue to areas such as wards being taken out of use. If an area is out of use temporarily,

a programme of flushing of outlets must be implemented until the area is brought

back into use again. If services are to be permanently halted in an area then the hot

and cold supplies should be switched off and the pipework removed back to the

furthest junction possible so as not to leave any dead legs in the system which couldharbour legionella.

The choice of pipe material used and the way it is jointed is also important. Debatecontinues about the merits or otherwise of using modern plastic piping in hot and cold

water supply systems. Critics quote its poor mechanical strength and need for

extensive support brackets compared to copper tubing. Poorly installed plastic pipe

may have extensive sagging along its length which could negate some of the benefits

of flushing. There is a question mark over whether or not leaching of material maytake place from plastic pipe over time, material which could add to the nutrient base

available to the legionella bacteria. Copper remains the material of choice and is

especially suitable for use with modern chlorine dioxide plant as it is resistant to

chlorine at recommended levels. Pipe jointing materials such as hemp and linseed oil

based compounds should never be used in potable water systems as they are

biodegradable and provide a nutrient rich source for bacteria. Modern compression

fittings as well as the use of soldered joints negate the need to use such products.

Avoid using jointing products such as hemp which could favour the growth of legionella


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5. Maintenance of water storage and delivery

systems

5.1 Cold water storage tank cleaning

The cold water storage tank could be a vulnerable link in the water supply chain.

Traditionally the cold storage tank suffered from the out of sight, out of mind mentality as

by its nature the cold water tank is usually situated high up on a rarely visited roof or

inaccessible attic space. Uncovered tanks with little or no insulation against heat or cold were

the norm up to quite recently and unfortunately can still be found in operation today.

Uninsulated cold water storage tanks will suffer huge temperature swings due to the effects of

sunshine in the summer and frost in the winter. An un-insulated tank situated on a roof or in

an attic space will undoubtedly break the recommended cold water temperature maximum of

20C during the summer months. If light is allowed to penetrate into the tank due to badly

fitting covers or no covers at all, this will encourage the growth of algae in the tank,

especially at the water line and this algae will provide a nutrient base for the legionella

bacteria. Cleaning of the water storage tank on an annual basis is the key to maintaining the

water quality within the tank. It is important that cleaning is undertaken by trained personnel

and that the task is governed by a standard operating procedure. Staff must adhere to the

SOP and proper records must be kept. A typical SOP for water storage tank cleaning should

include the following:

Notice must be given to the occupants of any parts of the building to be affectedduring the water outage period

Drawings of the supply system downstream of the storage tank to enable theoperatives to valve off and isolate the tank correctly

Instructions to the cleaning operatives about personal protective equipment to be used


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Step by step instructions about how precisely the cleaning is to be carried out, whatchemicals are to be used for disinfection and in what quantities

Instructions around any flushing of the supply system downstream of the tank withthe diluted chemical disinfectant and subsequent flushing with clean water.

Proper record keeping to include the date of the cleaning, the names of the operativesinvolved and a record of any chemicals used and the quantities.

This 19,000 litre cold water storage tank had a poorly fitted lid and no insulation and is

situated in an area that suffers from huge solar gains in the summer. This tank was brought up

to standard by boarding out the gap between the bund wall and the tank and providing an

access stairs for cleaning and maintenance. The walls of the tank were cladded with 60 mm

of kingspan insulation panels secured with exterior batens. The roof of the tank was fitted

with 80 mm kingspan rigid interlocking panels into one of which a hinged access lid was cut.

Note the plumbing of the water meter to this tank. The meter is fitted in such a way that the

unused leg at the top of the photo can be left in a draining position so that it cannot provide a

potential breeding area for the legionella bacteria.


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5.2 Hot water calorifier cleaning

It is convenient to assume that once the calorifier temperature is kept above 60C, then this

part of the water delivery chain is safe from a legionella risk point of view. However this is

not the case. As we have seen already, debris and sludge gathers at the lowest point of a

calorifier over time and coupled with the lower return water temperatures entering the vessel

in the vicinity of these deposits, a favourable environment for the legionella bacteria may

exist. It is important therefore that the hot water calorifier is fully cleaned out on a regular

basis. This is not necessary every year but a good rule of thumb is to clean the calorifier,

check it again after three years and depending on its condition then, the cleaning interval can

be kept at three years or extended to a maximum of five years. This cleaning should be

undertaken by trained personnel with a working knowledge of the system as care must be

taken to ensure that no damage is caused to the heater battery coils or calorifier seals. Extra

care must be taken to ensure that debris from the calorifier is not allowed to enter the delivery

pipework during cleaning as this could potentially release legionella bacteria directly to the

end user water outlets.

Heater battery removed from a calorifier for cleaning, showing accumulated debris and

deposits which could provide a beneficial environment for bacteria


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5.3 Chlorine dioxide treatment

Chlorine has been recognised for a long time as being a useful disinfection agent in water

storage and supply systems. Hyper chlorination of water supply systems found to be infected

with legionella is an important tool in the battle against the bacteria, especially in Health care

facilities where higher than average numbers of susceptible people are concentrated. In such

situations and following a positive result for legionella, the facilities personnel will typically

raise the chlorine level in the affected cold water storage tank to 50 ppm and maintain it at

this raised level for one hour. The hyper chlorinated water is then flushed through the system

until a concentration of 30 ppm is measurable at the furthest sentinel cold outlet. The sentinel

tap should continue to be flushed for one hour and other cold outlets opened also. This

procedure is usually carried out in conjunction with a thermal treatment of the hot water

calorifier and supply pipe network. Similar to the procedure with the cold supply, the hot

water calorifier temperature is raised to 80C under controlled conditions and maintained at

this raised level for one hour before being released into the supply pipe system. The furthest

sentinel hot outlet is then opened and run for one hour to ensure that the entire supply system

is thermally treated at the raised temperature.

The process described above is however only designed for emergency use. It is not feasible or

desirable to maintain high levels of chlorine in a water supply system as a legionella control

measure. There are several reasons for this

Chlorine increases the rate of corrosion in copper pipes. A study of this by theUniversity of Iowa showed an increase in leaks on the supply system from 0.17 to 5

per month

High chlorine levels in water can lead to the formation of organic compounds calledtrihalomethanes and these have the potential to cause cancer. Another study by the

University of Iowa found that when the level of free chlorine in water was raised to

4ppm, the level of trihalomethane rose to 200g per litre or double the recommended

amount


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The benefits of using chlorine in water delivery systems can however continue to be realised

through its use as chlorine dioxide. Chlorine dioxide is produced by reducing sodium chlorate

in an acid solution. Chlorine dioxide in its gaseous state is highly unstable and therefore the

product is normally produced on site in a chlorine dioxide generator and injected directly into

the water stream to be treated. Some of the benefits of using chlorine dioxide in the cold

mains supply include

Chlorine dioxide is a registered biocide Proper use involves dilution in the treated water at concentrations too low to risk

corrosion of the delivery pipe network

Chlorine dioxide will tolerate substantial swings in the pH of the water Bacteria cant build up a tolerance against chlorine dioxide over time.

Chlorine dioxide works by initially destroying the biofilm present in all parts of the waterdelivery system and then preventing its re-growth. As noted already, this biofilm layer is

made up of amoebae and protozoa which naturally occur in water, as well as deposits of

organic material. Once the biofilm layer is destroyed, the legionella bacteria which parasites

on the biofilm organisms can no longer establish a foothold and is easily flushed out of the

system before it can form colonies large enough to cause legionellosis. The cleaning effect

that chlorine dioxide achieves on a water delivery system is easily observed in the following

areas

The water storage tank, especially at the water line where biofilm is likely to occur System ballcocks splashed by treated water are clean while those in untreated tanks

have biofilm deposits

Toilet cisterns served by chlorine dioxide treated water are clean while untreatedcisterns have biofilm present

The strainers of thermostatic mixing valves stay free of biofilm and other deposits Shower heads are cleaner


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The main disadvantage of using chlorine dioxide in legionella control programmes is that it

can lead to complacency. Unfortunately chlorine dioxide has come to be seen in some

quarters as a silver bullet for legionella but it is not. It is a useful tool in a comprehensive

legionella prevention programme, but Facilities Managers adopting a fit and forget

approach are likely to be disappointed.

The chlorine dioxide dosing system shown here, though only fitted in the last three years is

now considered to be old technology because it uses a three stage process beginning with the

blue container on the left which contains hydrochloric acid. This acid is diluted and passed

over the crystals in the white canisters where ion exchange takes place. Finally the solution is

delivered to the catalytic converter which is the grey cylinder on the right and the formation

of the chlorine dioxide gas is speeded up. This gas is then injected via a metering pump into

the incoming cold main. Failure at any point of the three stage process means that chlorine

dioxide is not being produced and the system is not being protected. Experience by the author

of working with this system shows that excellent results are possible but very close and

labour intensive monitoring is essential to ensure the un-broken delivery of chlorine dioxide

to the water stream. This system also exposes the operator to hazardous chemicals and the ion

exchange canisters are pressurised, creating another potential risk. There is also a rapid falloff in the efficiency of conversion of constituents to chlorine dioxide in older on site


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generators. Modern systems produce chlorine dioxide in a simpler and much less hazardous

way as they do not use corrosive acids. The system output is also improved with up to 95%

conversion to chlorine dioxide being achieved and maintained.

Tristel Technologies in-line dosing unit

This example of a modern chlorine dioxide dosing system has several advantages over the

older arrangements.

It uses two low risk chemicals, namely sodium chlorite and citric acid There is no fall off or gradual decline in the production of chlorine dioxide An alarm function on plant failure Lightweight and compact unit


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5.4 Automatic flushing systems

A viable legionella colony can develop in a water supply system in as little as seven days.

Areas where water services are infrequently or intermittently used are at risk. In Health care

facilities it is not uncommon for entire wards to be taken out of use for extended periods. This

could be due to budgetary constraints or refurbishment. Even in areas that are continually

occupied it is possible that one or more water outlets may receive little or no use. An example

would be a store room on a hospital ward that has always had a hand wash basin because it

was originally designed to be an examination room but is now stocked to the ceiling with

boxes, wheelchairs, Patient property, etc. Such a basin is seldom if ever used and the hot and

cold supply to it is at high risk of harbouring legionella.

Instigating a flushing regime as part of a legionella control programme involves the manual

flushing of infrequently used water outlets on a weekly basis. This is a labour intensive

exercise and in a Hospital environment is usually allocated to the Household staff. The reason

for this is that the individual Household staff member will know his or her allocated ward or

area intimately and will have a much better knowledge of what rooms are or are not in

regular use and hence what outlets will need to be flushed.

The labour intensive nature of such a manual flushing regime has already been noted and an

available or willing pool of staff may not be present in all situations. Automated systems are

now available for flushing of outlets and consideration of their use is definitely recommended

on new build projects. Retrofitting to existing systems is not however labour intensive, overly

intrusive or prohibitively expensive and should also be considered by the building services

engineer.


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The aquaflush unit shown here is similar to others available on the market. It can be

programmed to perform temperature checks on the hot and cold supply to sentinel outlets at

pre scheduled intervals.

It will also perform an automatic flushing of the hot and cold sentinel outlet on a pre-set time

schedule and send the resultant data wirelessly to a central monitoring station or building

management system.

The main benefits associated with automating the flushing of outlets include

Cost. Once installed there are no on-going labour or travel costs such as would be thecase with a manual system

Safety, the flushed water goes directly to drain Quick and easy installation Elimination of human error Wireless communication Accurate on-going record keeping

The main disadvantage of automated flushing is the fit and forget mentality that such

systems can nurture. An initial survey may identify what outlets need to be fitted with


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automated flushing devices but that survey will only be relevant for one weekthe time it

takes a legionella colony to become viable-. If an outlet subsequently goes out of use for

whatever reason and goes un-noticed, the system will again be vulnerable. The implications

of removing on-going human monitoring and intervention in any flushing regime need to be

carefully considered before deciding on the merits of automated flushing.

The shower outlet is recognised as probably posing the highest risk of legionella

contamination in health care facilities. Production of an aerosol containing traces of

legionella is more likely at a shower head that in most other situations where vulnerable

patients are likely to come into contact with the water supply. The nature of showering means

that water droplets are likely to enter the mouth and may possibly be aspirated into the lungs

of already immunosuppressed patients.

Self- purging shower pipework arrangement showing extra connection to drain

The recognition of this risk has led to the development of self- purging showers such as the

one shown here. The red and blue pipes represent the hot and cold supply to the mixing

valve. When the shower is turned on, rather than immediately supplying water to the

showerhead, the flow is instead directed through the white pipe to the waste water drain


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shown here in green through a special air vent which stops foul odours returning and

eliminates the possibility of any aerosol formation. When the supply pipes have been purged

and the desired supply temperature reached, the valve redirects the flow to the showerhead as

normal. In some models the spray plate on the shower head automatically detaches or moves

away from the rest of the showerhead when the shower is turned off so as to fully drain all

remaining water from the vicinity of the showerhead. This results in a fully dry showerheadwhere legionella is unable to survive

5.5 TMV and showerhead cleaning

Thermostatic mixing valves take separate hot and cold supplies and mix them in a pre-

determined ratio to produce water at approximately 41C which is the standard temperature

for shower water supplies. However water at this mixed temperature is also ideal for

legionella and any dirt or debris which may have accumulated at the TMV will provide a

foothold for the bacteria to grow. Showerheads are at similar risk as they are also in direct

contact with water at legionella friendly temperatures and this water may remain in the

showerhead fitting after the supply is switched off. The presence of limescale or other debris

in the showerhead will exacerbate the situation.

Proper cleaning and maintenance of TMVs and showerheads is therefore very important and

must be carried out at regular intervals as laid down in the HPSC guidelines. Thermostatic

mixing valves must be inspected and cleaned annually and showerheads quarterly. Standing

operating procedures for cleaning of both pieces of equipment must be produced by the

building services engineer and followed by the cleaning operatives involved. The SOP must

provide step by step instructions on the proper cleaning procedures to be followed as well as

other important considerations such as proper use of personal protective equipment. Proper

records of all cleaning must be maintained and made available to relevant authorities on

demand.


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6. Testing and record keeping

6.1 Quarterly water testing

Sampling and testing of the hot and cold water supply is a vital part of any legionella control

programme. Test results will allow the engineer to take a coordinated approach to planning

the legionella prevention programme and tests which show no instances of legionella

infection are an on-going verification of an effective prevention programme. Testing of

samples must be carried out by an accredited laboratory.

At the initial stages of a legionella prevention programme, testing should be carried out every

three months and all hot water calorifiers and cold water storage tanks should be represented

at each testing interval so that a complete assessment of the entire site can be made.

Following a series of clear test results, consideration may be given to extending the testing

interval to six monthly if there are budgetary constraints, but a better approach may be to

leave the testing interval at quarterly and cut down on the number of samples taken. This

approach means there is still a check on the prevention programme at timely intervals and

any instances of positive results can be actioned without undue delay. The Health Protection

Surveillance Centre sets out the following guidelines for dealing with positive legionella

results depending on the number of coliform units cfu - of the legionella bacteria

discovered.


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100 but


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If the remedial action fails to achieve reduced levels of legionella or if the system is found on

retesting to be clear and then subsequently becomes rapidly re-infected, this necessitates an

examination of the entire water supply network to try to ascertain the cause. If legionella is

breeding freely in the water supply system, this obviously means that favourable conditions

are occurring which encourage such growth. These conditions may be caused by recent works

carried out on the system which may have allowed debris to enter and act as a medium.Alterations to the supply pipe network may have inadvertently created dead legs within the

system where legionella can thrive. Whatever the reason it is vital that the proper remedial

action is taken without delay to return the water supply system to a safe condition for the end

user.


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6.2 Daily chlorine dioxide readings

The benefits accruing from the installation of a chlorine dioxide dosing system have already

been discussed. Monitoring of the amount of chlorine dioxide present in the water supply

system is important for the following reasons

To ensure that the chlorine dosing plant is operating correctly To ensure the amount of chlorine in the system does not exceed statutory limits To check that outlying areas are receiving the benefits of added chlorine

Testing may be carried out manually by Facilities staff or automatically by sensing the

chlorine levels present at the cold water storage tank and relaying the results via the BMS to a

central computer for monitoring and recording. The advantage of manual testing is that

results can be monitored at several different locations throughout the cold water supply

system without the need to install chlorine sensors and cabling to the BMS. The distribution

of the chlorine dioxide in the system is also more accurately measured by manual testing as a

different test location can be chosen each day.

Chlorine dioxide test kit from Hach Technologies
http://www.hach.com/chlorine-dioxide-pocket-colorimeter-ii-test-kit/product?id=7640442961&callback=qs


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Manual testing may be carried out by using the dilution method or a portable calorimeter

such as the Hach calorimeter above. The dilution method involves adding a re-agent and

free chlorine in liquid form to a water sample and determining the level of chlorine present by

the colour change in the sample.

This method is acceptable when checking that the chlorine dioxide plant is operating

correctly, but does not give detailed enough analysis to determine whether or not the correct

level of chlorine is being maintained throughout the system. The calorimeter on the other

hand is very accurate and will provide readings down to one hundredth of a millilitre.

The daily chlorine dioxide test begins with taking two ten millilitre samples of cold water

from the appropriate sentinel taps. The sentinel taps chosen should be the nearest and furthest

available cold outlets from the water storage tank. The calorimeter works by comparing the

levels of chlorine dioxide in one sample to the levels found in any previous sample. For this

reason the first sample taken is only used to zero the calorimeter so that the machine

compares the following real sample to a reading of zero chlorine and not to some

previously taken sample reading which may still be present in the calorimeter memory. The

second sample taken is prepared for testing by adding a chlorine re-agent to it and then a

sachet of free chlorine powder. The sample is agitated by shaking gently and is then placed in

the calorimeter which produces a very accurate chlorine dioxide measurement by passing a

beam of light through it. For chlorine dioxide to continue to be effective as a biocide in a

water distribution system, the level must be kept above 0.1 ppm. However levels must not

exceed 0.5 ppm which is the maximum allowable level for safe drinking water. Levels of

chlorine dioxide outside these parameters will necessitate adjustment of the central dosing

plant. Daily chlorine dioxide measurement is a time consuming and labour intensive

operation but should be seen as a vital component in any legionella prevention programme.

As with other testing, accurate records of chlorine dioxide levels must be kept and made

available for review on demand by relevant authorities.


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6.3 Monthly hot/cold water temperature testing

Monitoring the temperature of the hot and cold water supply is a good way to check whether

or not favourable conditions exist in the supply system for the growth of legionella. The

bacteria is inactive and cannot form colonies in water at temperatures under 20C.

Temperatures over 60C will quickly kill the bacteria. Legionella thrives best at water

temperatures around 35C and it is at this temperature that water systems may become

rapidly infected. A monthly temperature testing regime will quickly identify any areas where

optimum hot and cold water temperatures are not being maintained and remedial action can

then be taken. Temperature checks are carried out at sentinel hot and cold outlets. This

involves taking a temperature reading at the nearest and furthest hot and cold outlet from the

supply calorifier or cold water storage tank. The HPSC guidelines are as follows

Sentinel cold outlets must reach a temperature of below 20C within two minutes ofswitching on

Sentinel hot outlets must reach a temperature of over 50C within one minute ofswitching on

Temperature readings within these parameters indicate that there is no part of the hot and

cold water supply system where favourable conditions are being provided for the growth of

the legionella bacteria. Temperatures outside of these parameters should act as an alarm

signal that the water supply system may be vulnerable and a review of the supply network is

indicated. Possible reasons for temperature readings outside the accepted parameters could

include

Poorly insulated cold water storage tanks which may allow water temperatures in thetank to rise rapidly, especially during the summer months

Inadequately insulated or un-insulated hot water supply pipes suffering from highheat loss on route to the hot water outlet


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Poorly insulated cold water supply pipes suffering heat gains from nearby hot supplypipes or while passing through heated ceiling voids

Calorifier set point too low to maintain the water in the hot supply pipe at over 55C Poor plumbing practice leading to a crossover between the hot and cold supplies or

between the hot and hot return supplies

Poorly maintained hot return pumps failing to keep the water circulating in the supplypipework during periods of low load

As with all testing regimes, accurate records of temperature checks must be maintained.

These should be reviewed regularly and any necessary remedial action undertaken.

7. Interaction with other stakeholders

7.1 Medical staff education

In a health care facility it is all too easy for the various professions to adopt a blinkered

approach to their responsibilities around legionella control. The building services engineer

may be diligently implementing the Hospitals legionella prevention programme from an

engineering point of view but if he is doing so in isolation from the other professional

disciplines, then the control programme is not complete. It is vital that the engineer be in

regular formal and informal contact with all of the other stakeholders in the Hospital to

ensure that everyone is taking a co-ordinated approach to legionella control and prevention.

The medical staff and especially the nursing staff will already have a thorough knowledge of

the legionella bacteria from their medical training. They will know the risks associated with

the water supply system and how the bacteria enters the human body. Because they are in

constant contact with the hospital patients and will regularly assist many of them with

showering and bathing, they are a valuable asset right at the most dangerous interface where a

potentially vulnerable patient and a potentially infected water supply come together. It is vital


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that the medical staff think legionella prevention all the time. A good induction programme

will have a section on legionella prevention so that the Nurse or Doctor is aware before they

even take up employment that the Hospital or other health care facility takes legionella

prevention very seriously. Practical tasks that any nurse on the ward can carry out to aid the

fight against legionella include

Running the shower through one cycle before allowing the patient to use it Screening the patients so that potentially vulnerable people are given a pre-prepared

bath rather than being allowed to shower

Informing the Patients on a one to one basis of the risks associated with legionellaand what the Hospital does to control the bacteria

Liaise with the building services engineer on infrequently used or obsolete wateroutlets

7.2 Household/Catering staff flushing regimes

Household and Catering staff can play an important role in legionella prevention by ensuring

that infrequently used water outlets are flushed on a weekly basis.

This may seem to be a task which should be limited to the household staff on the hospital

ward but most hospital wards also have pantrys where the catering staff work and new

HACCP guidelines now state that catering sluice facilities must be separate from household

ones which usually means a separate sluice room which is under the control of the catering

staff.

The household and catering staff have two important roles in legionella prevention

1. To flush infrequently used water outlets2. To pass information to the building services engineer which may allow disused outlets

to be de-commissioned


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1. Both the household and catering staff are ideally placed to implement a flushingregime at ward or office block level. They have an intimate knowledge of all parts of

the building that they are responsible for cleaning. They will often build up a

relationship with the patients on the wards and will always know in advance if an

ensuite room is vacant or planned to be vacant. Some hospital wards close during

certain parts of the year due to decreased demand or budgetary constraints but thehousehold staff still remain on duty and are then even more important to the legionella

prevention programme. Any flushing regime implemented must be a formal

arrangement agreed with all of the relevant staff and implemented throughout the

organisation. Vulnerable areas left out of the flushing regime will render the rest of

the exercise useless as legionella colonies flourishing in neglected areas will

inevitably spread to the rest of the system through the distribution pipework.

A flushing sheet should be prepared by the building services engineer and distributed

to the household and catering staff at ward level by their managers. The flushing sheet

should have clear instructions on how to flush an outlet and should stress the

importance of using personal protective equipment during the flushing exercise.

Staff then fill in the forms weekly, noting what outlets were flushed and return them

to the manager who forwards them on to the building services engineer for review and

filing.

2. Household and catering staff will have a good idea from their flushing exercise ofwhich outlets are used infrequently and may discover outlets within their area of

responsibility which are never used at all. It is a good idea to leave space on the

flushing sheet where staff can note such outlets so that the engineer can assess

whether or not to remove them from service entirely so as to avoid dead legs where

legionella could flourish. When such action is taken and credited back to the staff

member who originally identified the outlet, this acts an encouragement and makes

the staff members feel that they are an important link in the legionella control

programme.


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7.3 Circulation of information/test results

The infection control committee of a hospital is usually the body tasked with implementing

and monitoring the legionella prevention programme. The committee will include

representatives from all disciplines within the hospital including a building services engineer

and hopefully a microbiologist. It is to this committee that the building services engineer will

initially report any legionella test results and on-going developments in the control

programme. However it is important that information around legionella be circulated as

widely as possible so that all staff members are encouraged to play their part in the on-going

fight against the bacteria. An open and honest dialogue between all staff members in relation

to legionella encourages inclusion and the feeling of ownership by individual staff members

of the legionella prevention programme.


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8. Case studiesIntroduction:

For my case studies I have chosen to examine the existing situations

pertaining to two hospitals, namely Basildon University Hospital near London and St

Patricks University Hospital in Dublin.

I chose Basildon University Hospital for the following reasons

It is situated in a neighbouring Country with similar legislative requirementspertaining to legionella control as Ireland

It has suffered fatalities which were directly linked to legionella It has suffered recent legionella fatalities-August 2011- The Basildon area was topical at the time of writing as the authorities were engaged in

evicting Irish traveller families from a long established but illegal encampment at

Dale Farm.

I chose St Patricks University Hospital because I work there in the Facilities Department as

assistant foreman and I am directly and intimately involved in the Hospitals legionella

control programme. I report to the facilities Manager, Eamonn O Reilly who is the designated

Responsible person for legionella prevention within the Hospital.


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8.1Basildon University Hospital

Basildon University Hospital is a large NHS Trust hospital with approximately 800 beds. It is

situated in Essex in England and is 25 miles east of London. It provides multi-disciplinary

care to the surrounding community including accident and emergency, cardiology, oncology

and general surgery departments. It is on a large site and consists of several interconnected

buildings. The hospital has an unenviable association with the legionella bacteria including

The death of a Patient who contracted legionellosis whilst being treated in the hospitalin August 2011

Three cases of legionella infection in patients in 2010 which were attributed to thehospital. One patient died and the other two responded to treatment

Three deaths at the hospital in the last nine years were found to be from legionellosiscontracted by patients during their time in the hospital

A fine of 25,000 was imposed on the hospital in connection with the death of a malepatient who contracted legionellosis in 2002

Legionella infection was linked to the deaths of two patients at the hospital in 2007and 2010 but inquest results on these have not been finalised to date.

The Hospital has had very negative media coverage arising from the various outbreaks of

legionella infection on the site. It has also been criticised over the higher than normal

mortality rate in its accident and emergency department. An unannounced inspection by

inspectors from the Care Quality Commission found unacceptable levels of hygiene and

patient care at the unit.

Given the amount of negative media exposure endured by the hospital over the years, it

would not be unusual if Management personnel there adopted a bunker mentality when it

came to disseminating information for public consumption but in any case there is very little

useful information available concerning the engineering methods employed by the hospital to

try to combat the level of legionella present in its water distribution systems.


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In an effort to obtain an overview of the hospitals legionella control strategy, I wrote to the

National Health Trust involved and also directly to the Facilities Manager at the hospital. A

copy of that letter is included in the appendices to this document. By the submission date for

my dissertation, I had not unfortunately had any reply from Basildon Hospital Trust or from

the Facilities Manager at Basildon Hospital. However an online news item may give some

idea of the steps that have been taken by the Hospital. A spokesperson told BBC News thatthe Hospital has spent two million pounds sterling on remedial works to the plumbing system

in the Hospital since the first incidence of legionella infection was discovered in 2002. The

spokesperson added that the Hospital has a strict regime of chemical dosing of the water

system in place and also carries out thermal disinfections of the water supply system. Finally

the spokesperson said that a comprehensive monitoring procedure for legionella control is in

place.

I would make the following observations about the Hospital statement.

Two million pounds is a very substantial sum of money to spend on remedial works toa plumbing system. I would be interested to know how the decision was made to

spend this money and how it was decided what works to carry out. The first step

should have been to have an independent legionella risk assessment carried out for the

entire site. This would have highlighted the areas and the services that were most at

risk of infection and allowed the Hospital management to target the available funds to

where the biggest payback was achievable.

Chemical dosing of the water supply system is a useful tool in legionella control butshould not be considered as a magic bullet. Adding chlorine in some form to the water

supply network at continual low concentrations kills the biofilm which harbours the

legionella bacteria and prevents its re-growth. Chemical dosing should be considered

to be a backup to good system management but never a substitute for it.


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Thermal treatment of the hot water supply system is a very labour intensive task andshould not be used as part of a regular maintenance programme. Thermal treatment is

useful following a positive legionella test result as it allows the system pipework to be

quickly purged of any remaining bacteria. The results are temporary however and if

the underlying reasons for the initial infection are not addressed, the system will be

rapidly re-infected. Thermal treatment requires the cooperation of a large number ofstaff to ensure that patients are not put at risk of scalding as the water in the calorifier

is raised to 80C before being released at this elevated temperature to the various

outlets being treated.

Which monitoring procedures are in place? and does this monitoring include thefollowing

1. Daily chlorine concentration measurements2.

Hot and cold water temperature checks

3. Regular independent testing of water samples Is a flushing regime in place in the Hospital for seldom used water outlets? A properly

run flushing regime implemented on the ground by staff who know the occupancy

patterns for a given area is very effective in preventing favourable breeding conditions

for the legionella bacteria. It also allows staff to buy into the idea of legionella

prevention in a practical way


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8.2 St Patricks University Hospital

St Patricks University Hospital is one of the leading psychiatric hospitals in Ireland. It can

accommodate approximately 300 Patients. It is the oldest purpose built psychiatric hospital in

Europe. The original building which still stands today was willed to the people of Dublin by

Jonathan Swift for use as a psychiatric hospital and it has been in continuous use as such

since the year 1745. The Hospital campus has developed in a piecemeal fashion over the

intervening years so that today accommodation is spread across several different buildings

both large and small, with each having its own hot and cold water services.

St Patricks University Hospital has never had a confirmed or to my Knowledge, suspected-

case of legionellosis. However, in 2008, higher than acceptable levels of the legionella

bacteria were found to be present in water samples when sent for analysis. Under present

guidelines, levels of bacteria exceeding 1000 cfu necessitate remedial action to be undertaken

and such levels were found to be present in a sample from one ward area. At the time, the

facilities department dealt with the problem by thermally treating the hot water supply to the

affected ward and chlorinating the cold water supply. This purged the system of the bacteria

and subsequent tests came back negative for legionella. Following this incident, an internal

review of systems for the control of legionella was instigated which resulted in the

appointment of an external expert to carry out a full risk assessment of all the hot and cold

water services in the Hospital and the systems in place for controlling and monitoring the

legionella bacteria.

Mr Bill Harley is an independent water services engineer from Scotland. He has worked

extensively with the NHS in Britain and Northern Ireland on legionella control for hot and

cold water systems. He is a Director of the CADHAM Consultancy Group and is engaged in

legionella control programmes with several health care facilities in Ireland. He carried out a

full legionella risk assessment in St Patricks University Hospital during the summer of 2008.

This involved several site visits to inspect the plant and to review the existing control

measures and documentation. The risk assessment discovered many failings and


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short-comings in the legionella control programme in place in the Hospital at that time but

also provided a platform on which the Hospital could build a co-ordinated programme going

forward. The Hospital now has a system for monitoring and controlling the bacteria that

complies with best practice in the industry and more importantly complies with the law as it

stands in Ireland. The legionella monitoring and control programme now in place in the

Hospital has many elements

The Building Management System BMS- plays a very important role in legionellacontrol. The BMS is a computer software programme which allows the user to

monitor and adjust various aspects of a building such as heating, ventilation and hot

water systems. The St Patricks Hospital BMS was already monitoring the flow

temperatures of the hot water systems. Following the risk assessment, temperature

stats were fitted to the return pipework also. For legionella control, it is important to

maintain the hot water temperature in the calorifier at a minimum of 60C and the

temperature of the water returning to the calorifier should not fall below 50C. If the

flow or return temperatures fall below their pre-set levels, an alarm will activate on

the BMS and the facilities department will investigate the reason for it. The reason

could just be heavy usage of the hot water available at certain times of the day and

the temperature will recover quickly. However if the reason was a pump or boiler

failure and the BMS was not monitoring the system, then water could lie in the pipe

work at a temperature that would facilitate rapid growth of the legionella bacteria.

This water could then potentially be delivered to a shower outlet being used by a

patient with a compromised immune system. An important aspect of the building

management system recognised by Bill Harley following his recently completed bi-

annual review was the ability to store historical water temperature data so that this

could be reviewed on a regular basis. This allows an assessment to be made as to

whether hot water temperatures are likely to be falling below minimum levels for

periods of time long enough to encourage bacteria growth. The Hospital has had thisfacility added to the BMS by the system management company.


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The risk assessment highlighted many shortcomings in the cold water storagefacilities in the Hospital. Many storage tanks were old and un-insulated; some were

not even covered. The Hospital undertook a full review of all the cold water storage

tanks and implemented a remediation plan. All water storage tanks were fitted with

water meters to make sure they were sized properly. This is important as only twenty

four hours of stored water should be available in a cold water storage tank to allowfor interruption of supply. Any more than this means that there is not enough

throughput of water and during a hot summer day this excess water is rapidly heating

up to a temperature that would favour the growth of the legionella bacteria. Sizing the

water storage capacity properly allowed the Hospital to consolidate three separate

storage tanks into one and the two older tanks were then disconnected and taken out

of use. All modern water storage tanks have inbuilt insulation and hinged access

covers for maintenance and

Documents

Legionella Control in Healthcare