Reducing the risk of Legionella - Home - KELSI€¦ · Web viewThe Health and Safety Commission give practical guidance on the ... ( to be fitted with low level drain valve

REDUCING

THE RISK FROM

LEGIONELLAE

IN HOT AND

COLD WATER

SYSTEMS

WITHIN

BUILDINGS

January 2001 Control of LegionellaeAmended 2007

Reducing the risk from

Legionellaein hot and cold water

systems within buildings

CONTENTSIntroduction 2

Guide to Code 4

Risk Assessment (including Premises Risk Categories) 5

Design Requirements 6

Regular Maintenance RequirementsHigh Risk - Category I Premises 10

Medium Risk - Category II Premises 14

Low Risk - Category III Premises 18

Appendix 1Disinfection of Cold Water Storage Tanks 22

Appendix 2Chlorination of Water Storage Tanks, Vessels and Associated Services 23

Appendix 3Chlorination of Mains Water Services 26

Kent Property Services - Contacts 27

Dated this update - January 2001Ammended 2007

KCC Education and Young Persons1

Control f Legionellae January 2001Amended 2007

INTRODUCTION

This Code of Practice is a KCC policy document for use by all managers having a responsibility for Kent County owned and leased property and is a revised version of the Code issued in May 1992 to encompass up to date knowledge on Legionallae Control.

All Heads of Establishments have responsibility for ensuring that the relevant work listed in this code is implemented.

Legionnaires disease (Legionellosis) is a form of pneumonia which can be life threatening. Legionellae bacteria are naturally occurring in water and will multiply to high levels of contamination in hot and cold water systems if provided with nutrients from rust, sludge, scale or organic jointing compounds and provided with suitable ambient temperatures.

Contraction of the disease is from inhaling an aerosol vapour of contaminated water droplets from items such as a shower, spray taps, filled baths, water cooled air conditioning.

Those most at risk are the elderly, persons with an underlying illness, persons using immunosuppressant drugs and smokers. Males are more likely to be affected than females and most reported cases have occurred in the 40 to 70 year age group.

The risk from building services are reduced by good design and regular maintenance and the purpose of this code is to set the minimum standards required to provide clean hot and cold water systems operating at correct temperatures in all Kent County Council owned and leased commercial buildings.

The code does not apply to domestic premises which are considered low risk as the total water content of domestic systems changes at a rate normally sufficient to limit any problems.

Compliance with this code is likely to satisfy the salient items of the Health and Safety Executive Guidance Note on this subject.

Kent Property Services will be pleased to provide help and assistance to clients on the implementation of these standards. Details of contacts can be found on page 27.

2 KCC Education and Young Persons


NOTE:

The Health and Safety Commission give practical guidance on the requirements of the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health (COSHH) Regulations 1994 with regard to the risk of Legionellosis.

A substance Hazardous to Health includes a micro-organism which creates a hazard to anyone’s health. Managers should remember that the Health and Safety at Work etc. Act 1974 imposes a personal responsibility to enforce COSHH.

The chemicals referred to within this code should also be included in the premises COSHH assessment. Manufacturers’ safety instructions must be strictly adhered to by all personnel using these chemicals, i.e., Sodium Hypochlorite, kettle descaler and Milton 1.

The HSC Approved Code of Practice - L8 (Rev) - entitled “The prevention or control of Legionellosis (including Legionnaires’ disease)” which came into effect on 16 January 1995 states:

Because of the nature of the risk and the diversity of its sources, it is important that potential risk situations be assessed individually and that appropriate precautionary measures are adopted and are supported by a suitable management regime.

ACKNOWLEDGEMENT:

This document has been prepared for:KENT COUNTY COUNCIL - PROFESSIONAL SERVICES DEPARTMENTBy: Tony Monk County Environmental Health Officer - Personnel and Training

David Leggett Senior Engineering Surveyor - Kent Property ServicesCharles Tanswell Chief Engineer & Business Manager - Kent Property Services

Copies may be obtained from:Kent Property Services, Technical Library, Springfield, Maidstone, Kent.

COPYRIGHT OF THIS CODE OF PRACTICE IS VESTED IN KENT PROPERTY SERVICES ON BEHALF OF KENT COUNTY COUNCIL.

KENT COUNTY COUNCIL - KENT PROPERTY SERVICES - OCTOBER 1996.

Designed & Produced by Kent County Council Design Studio 01622 696262



GUIDE TO CODE

Your premises will fall into one or more of the risk categoriesdetailed within the Risk Assessment on page 5. Select theRisk Category for your particular premises and then turnto the appropriate sections within the code which havebeen divided between Design and RegularMaintenance.

The Design requirements on page 6 apply asappropriate to all premises and a survey will benecessary to:

i) determine if any modifications are needed to the hot or cold water services of your premises to meet the requirements of this code

ii) to ensure that there are suitable records documents.

The Regular Maintenance requirements that should be arranged are detailed for the High Risk Category I on page 10, Medium Risk Category II on page 14 and Low Risk Category III on page 18.

In order to comply with this Code of Practice you are advised to:

Consult Kent Property Services Area Building Surveyor, whenever you are considering work to hot and or cold water services. Your nearest contact may be found on Page 27.

Only employ accredited designers and contractors who have the necessary knowledge to conform to this code. Advice may be obtained from Kent Property Services.



RISK ASSESSMENT

In preparing this Code of Practice a risk analysis was carried out which took into account the following factors:-

i) Types and sizes of buildings.

ii) Hazard and risk from Legionallae and other pathogenic organisms.

iii) Hazard and risk from scalding due to higher water temperatures.

iv) Presence of aerosol producing water outlets.

v) Susceptibility of client/staff groups to contracting Legionnaires disease and/or vulnerability to scalding through handicap/infirmity.

vi) Hazard and risk from the use of descalers and disinfectants.

With these criteria in mind premises and their associated client/staff groups have been placed in the following three premises risk categories.

High Risk - Category I Premises

Residential or Day Care Centre for the Elderly.Residential or Day Care Establishment for Adults with High Dependency Needs.Schools/Establishments for Children with Severe Learning Difficulties and or Physical Disabilities.

Medium Risk - Category II Premises

Schools and other premises where showers are in general use by adults.

Low Risk - Category III Premises

Schools and other premises with:

i) No shower facilities

ii) Showers not used by adults.



DESIGN REQUIREMENTS

The following items apply to all categories of risk and are the minimum design requirements that should be provided in all existing KCC owned and leased premises.

This Code of Practice has been prepared after a series of discussions with representatives from the Health and Safety Executive. A timescale has been previously set for the provision of modifications to existing hot and cold water installations to comply with this and previous codes.

To comply with this timescale all items should be carried out immediately if not already provided or by the date indicated.

Records

Prepare suitable record documents detailing:

Compliance with or action taken against all items listed below.

The name of the person or persons appointed to take managerial responsibility and to provide supervision for the implementation of precautions.

The name of the person or persons who have responsibility for implementing the requirements of this code.

Cold Water Storage Tanks

All storage tanks:

to be fitted with adequate tight fitting metal or plastic covers.

overflows to be fitted with protective screen to meet BS 6700 1987.

to be fitted with low level drain valve (Complete by May 1998).

To be protected from excessive solar or other temperature gain e.g., tank rooms constructed from glass walling or wooden cladding and tanks located in boiler rooms (Complete by May 1998).



to be sized to provide cold water storage capacity for an average one working day use. Where systems that are comprised of more than one tank exceed this capacity disconnect and, where practical remove tanks not required. (Complete by May 1998).

Ideally use one tank only with inlet and outlet at opposite ends. Where two tanks are required to provide sufficient storage, connect separate down services to each tank or connect in series at low level with inlet in one tank and down service(s) from the second tank.

No tanks shall be connected in parallel configuration (i.e., so that no tank is likely to contain stagnant or slow moving water.)

If a tank requires replacement due to corrosion or oversize renew with a plastic tank to confirm to current water bylaws requirements. KCC has a practice of not relining cold water storage tanks.

Expansion Pipes

No expansion pipework shall vent over coldwater storage tanks(Completeby May 1998).

Tank Rooms

All tank rooms to be lockable to preventunauthorised access and structurallysound to prevent ingress of birds androdents.

Hot Water Systems

Water heating plant shall ensure that the temperatures at all water storage vessels secondary tappings (i.e., flow and return pipework connections) will sustain the following standards:


flow 60C minimum, return 50C minimum.







Where possible, for showers in Category I and II premises, preference should be given to instantaneous type water heaters fitted with a high limit thermal cut out and fed by mains supply potable water.

All domestic hot water storage vessels shall have facilities for annual removal of sludge and loose scale. (Complete by May 1998).

The temperature of all hot water must be reduced at local point of use by mixing valve/tap, to safe temperatures to prevent scalding.

Outlets serving baths, showers and hair sprays shall be at 43.5C (+2C/-3C).

Standby pumps shall not be installed to domestic how water service secondary pipework. Remove any such pumps previously installed and store on site in case of a failure of the other pump.

Other than for pasteurisation, avoid temperatures in excess of 65C as this leads to rapid scale formation.

New Systems

All new cold water pipework shall be installed to reduce heat gain. Cold pipework shall be installed below hot pipework in order to reduce heat gain and both services shall be insulated.

All new tanks, hot water storage vessels and associated pipework systems shall be chlorinated before handing over to premises user as detailed in Appendix 2 and 3.



Drinking Water

All drinking water taps shall be clearly labelled.

Redundant Services

Following all refurbishment and adaptation works and work associated with change of use within premises, disconnect and where possible remove all redundant water services pipework, outlets and water using equipment

to prevent the possibilities of stagnant water in water pickets and dead legs.

Ensure all maintenance, refurbishment and adaptation works are undertaken without creating pipework dead legs exceeding 500 mm.

Standards

All new hot and cold water systems are to be designed to standards recommended by British Standard 6700, the Chartered Institution of Building Services Engineers (TM13), the Department of Health and Social Security, the Health and Safety Executive and the Water Undertakers Bylaws with particular reference to bylaws relating to tanks and cistern supply air gaps (see Model bylaws 11, 12 & 30 within the Water Supply Bylaws Guide issued by the Water Research Centre).

All fittings and materials to comply with BS 6700 and the Water Fittings and Materials Directory issued by the Water Research Centre.



REGULAR MAINTENANCE REQUIREMENTS


Arrangements should be in place for implementation of the following maintenance items at the specified frequencies. All tasks may be undertaken by approved contractor(s). Some tasks may be undertaken by suitably trained caretaking and or other staff employed at each premises depending on site conditions.

RecordsPrepare and regularly monitor suitable record documents detailing:

The action taken throughout each annual period against all items listed below.



Weekly Requirements Flush/operate any water using plant that is subject

to infrequent use i.e., permanently plumbed inemergency eye wash baths, temporary out of useshowers, etc.

Where a cold water pressurisation unit is installedwith run and standby pumps, arrange to change overthe pump operation to even out the wear on bothpumps.

Monthly Requirements Measure the temperature at the secondary tappings (i.e., flow

and return pipework connections) of all domestic hot water storage vessels to ensure:

60C minimum flow and 50C minimum return.(Readings from suitably installed thermometers is acceptable).



If test does not meet these requirements then remedial action to improve plant performance should be carried out.

The frequency of these monthly tests may be reduced to quarterly tests following repeated satisfactory monthly tests over a continuous six month period. If any subsequent test fails then these tests should revert to a monthly frequency.

Quarterly (3 Monthly) Requirements

Maintain all Shower/Spray Heads in accordance with the method below.

The minimum frequency shall be increased if found necessary due to site conditions and hard water scaling or after any period of disuse of two weeks or more.

The frequency between maintenance shall be spread as evenly as possible over a 12 month period determined by premises occupancy. Two of the maintenance dates may be arranged to coincide with the six monthly mixing valve service specified on page 12.

Suggested programme for schools:

Start of term - (April)End of Summer Term - (July) with mixing valve serviceStart of Autumn Term - (September)Start of Spring Term - (January) with mixing valve service

Method

The following actions are recommended:

Fixed shower heads. Remove spray rose and soak in 1:10 solution of Milton 1 and water for ten minutes. Wipe out inside of shower head with Milton 1 solution using a clean cloth. Rinse spray rose in water and descale with a kettle descaler. Rinse spray rose. Run shower at full flow and highest temperatures for five minutes. Replace rose.

Spray heads on flexible hoses, including instantaneous showers. Remove head and, if possible, the flexible hose. Soak head, and hose if removed, in a 1:100



solution of Milton 1 and water for at least one hour. (1:100 solution equals 50 mls or approximately 5 dessert spoons of Milton 1 to 5 litres or 1 gallon of water). Replace hose and run for five minutes as above. Rinse spray head and descale with kettle descaler. Rinse and re-assemble.

NB: Wear rubber gloves when handling Milton 1 or descaler as they are mildly corrosive. Do not mix the two chemicals together.

Six (6) Monthly Requirements

Service mixing valves by specialist contractor and maintain shower/spray heads as described above.

All water softeners, filters and scale reducers shall be maintained in accordance with manufacturers instructions.

Increase frequency if required due to hard water and excessive scaling.

Annual Requirements

All cold water storage tanks to be inspected by a competent person to ensure:

That tanks are free of organic matter, excessive sediment, scale or substantial corrosion. Where tanks require cleaning, disinfection shall be carried out after all cleaning work is completed as detailed in Appendix 1. If organic matter is found, i.e., dead birds or rodents, storage tanks and associated pipework systems shall be chlorinated as detailed in Appendix 2.

All storage tank lids and covers to be securely in place.

Tank room security is being maintained to prevent unauthorised access and that building structure has not deteriorated to allow ingress of birds or rodents.

All tank walls free of ivy and other plants.

Ensure all thermal insulation is undamaged, in sound condition and fixed securely.



Arrange flushing of sludge and loose scale from all domestic hot water storage vessels. On completion raise total contents of vessel to 60C for one hour in order to pasteurise the contents.

Four (4) Yearly Requirements

Arrange for descale of all domestic hot water storage vessels (except self cleaning stainless steel and glass lined vessels) and replace all gaskets. On completion pasteurise total contents of vessel at 60C for one hour. Increase frequency of descaling if found necessary.

Requirements following periods of Plant Shutdownand/or Premises Closure

For all shower/spray heads that are out of use for two weeks or more, carry out maintenance and cleaning as detailed under quarterly requirements above.

For all domestic hot water storage vessels out of use for one week or more, the water temperature shall be raised to maximum operating temperature throughout for at least one hour before being brought back into use.

After any period of premises or part premises closure of one week or more, discharge hot water until maximum operating temperature is obtained at all showers, taps, and other outlets to flush system through.

After any period of premises or part premises closure of 8 weeks or more, the above shall be disregarded and the following shall apply:

i) isolate and drain down all water services.

ii) all hot and cold water systems shall be chlorinated before being brought back into use as detailed in Appendix 2 and 3.





The risk in these premises or part of these premises may be reduced to a Low Risk Category III level if all shower facilities are provided by instantaneous type water heaters fed by potable water.

Where all showers used by adults within these premises are supplied from dedicated hot water storage vessels that maintain a secondary flow temperature of 60C minimum and secondary return temperature of 50C minimum measured at the storage vessel tappings, then the adult shower services shall be treated as Category II and the remainder of the premises shall be treated as Category III.

Where neither of the above apply the premises, or relevant part of the premises shall be considered as a Medium Risk - Category II premises and arrangements should be in place for implementation of the following maintenance items at the specified frequencies. All tasks may be undertaken by approved contractor(s). Some tasks may be undertaken by suitably trained caretaking and or other staff employed at each premises depending on site conditions.

Records

Prepare and regularly monitor suitable record documents detailing:

The action taken throughout each annual period against all items listed below:



Weekly Requirements

Flush/operate any water using plant that is subject to infrequent use i.e., permanently plumbed in emergency eye wash baths, temporary out of use showers, etc.



Where a cold water pressurisation unit is installed with run and standby pumps, arrange to change over the pump operation to even out the wear on both pumps.





Suggested Programme for schools:


Method



Spray heads on flexible hoses, including instantaneous showers. Remove head and, if possible, the flexible hose. Soak head, and hose if removed, in a 1:100 solution of Milton 1 and water for at least one hour. (1:100



solution equals 50 mls or approximately 5 dessert spoons of Milton 1 to 5 litres or 1 gallon of water). Replace hose and run for five minutes as above. Rinse spray head and descale with kettle descaler. Rinse and re-assemble.



Service mixing valves by specialist contractor and maintain shower/spray heads as described above.

All water softeners, filters and scale reducers shall be maintained in accordance with manufacturers instructions.

Increase frequency if required due to hard water and excessive scaling.

Annual Requirements

All cold water storage tanks to be inspected by a competent person to ensure:








Measure the temperature at the secondary trappings(i.e. flow and return pipework connections) of all domestichot water storage vessels to ensure:

flow 60C minimumreturn 50C minimum.

Arrange flushing of sludge and loose scale from alldomestic hot water storage vessels. On completionpasteurise total contents of vessel at 60C for one hour.


Arrange for descale of all domestic hot water storage vessels (except self cleaning stainless steel and glass lined vessels) and replace all gaskets.

On completion raise total contents of vessel to 60C for one hour in order to pasteurise the contents. Increase frequency of descaling if found necessary.

Requirements following periods of Plant Shutdown and/or Premises Closure











Arrangements should be in place for implementation of the following maintenance items at the specified frequencies. All tasks may be undertaken by approved contractor(s). Some tasks may be undertaken by suitably trained caretaking and or other staff employed at each premises depending on site conditions.

Records

Prepare and regularly monitor suitable record documents detailing:

The action taken throughout each annual period against all items listed below.



Weekly Requirements

Flush/operate any water using plant that is subject to infrequent use i.e., permanently plumbed in emergency eye wash baths, temporary out of use showers, etc.

Where a cold water pressurisation unit is installed with run and standby pumps, arrange to change over the pump operation to even out the wear on both pumps.







Suggested Programme for schools:


Method



Spray heads on flexible hoses, including instantaneous showers. Remove head and, if possible, the flexible hose. Soak head, and hose if removed, in a 1:100 solution of Milton 1 and water for at least one hour. (1:100

solution equals 50 mls or approximately 5 dessert spoons of Milton 1 to 5 litres or 1 gallon of water). Replace hose and run for five minutes as above. Rinse spray head and descale with kettle descaler. Rinse and re-assemble.





Service mixing valves by specialist contractor andmaintain shower/spray heads as described above.

All water softeners, filters and scale reducersshall be maintained in accordance with manufacturersinstructions.

Increase frequency if required due to hard water andexcessive scaling.

Annual Requirements

All cold water storage tanks to be inspected by a competent person to ensure compliance with:






Measure the temperature at the secondary trappings (i.e. flow and return pipework connections) of all domestic hot water storage vessels to ensure:

flow 50C minimumreturn 45C minimum.

Arrange flushing of sludge and loose scale from all domestic hot water storage vessels.




Arrange for descale of all domestic hot water storage vessels (except self cleaning stainless steel and glass lined vessels) and replace all gaskets. Increase frequency of descaling if found necessary. On completion raise total contents of vessel to 60C for one hour in order to pasteurise the contents.

Where pasteurisation is not possible, ensure vessel is isolated from system, refill storage vessel to ¼ full, dose with sodium hypochlorite to achieve 50 ppm (mg/litre) when vessel is full, continue filling to capacity, test to ensure 50 ppm of chlorine is present, leave for 2 hours, drain and fill with clean water.

Requirements following periods of Plant Shutdownand/or Premises Closure









APPENDIX 1

Disinfection of Cold Water Storage Tanks

The following is a specialist procedure and must be carried out by a competent contractor:

Valve off Cold Water down service.

Close supply valve and drain tank through bottom drain outlet, stirring to disturb and remove sludge/sediment.

Clean tank as necessary and wash down with clean water with bottom drain outlet open.

Close drain cock, open supply valve and refill tank to ¼ full.

Dose with sodium hypochlorite to achieve 50 ppm (mg/litre) when tank is full.

Continue refilling tank to overflow level, stirring water occasionally to achieve even distribution of chlorine within tank.

Test to ensure that 50 ppm of chlorine is present.

Leave for 2 hours.

Drain and refill to normal level with clean water.

Open cold water down service(s).

Note:

Check to ensure that any water containing chemicals, when discharged to waste, does not contravene any Water Authority Regulations.

No water containing high dosage of chlorine shall be allowed to enter the cold water down services.



APPENDIX 2

Chlorination of Water Storage Tanks, Vessels and Associated Water Services

The following is a specialist procedure and must be carried out by a competent contractor

Preparation for existing contaminated services

Valve off all cold water down services at relevant storage tank.

Close supply valve and drain down tank through bottom drain outlet stirring to disturb and remove sludge and sediment.

Remove all visible dirt and debris and clean tank.

Wash down tank with clean water through bottom drain outlet.

Open all cold water down services at tank, all taps and other drain off fittings and drain entire system.

Close cold water down services at tanks, tank drain and all taps and other draw off fittings.

Preparation for new systems

Remove all visible dirt and debris and clean tank.

Fill tank and system with clean water.

Close tank supply valve and drain down system through all taps and other draw off fittings.

Close cold water down services at tank, all taps and other draw off fittings.



Chlorination

Carry out above preparation as relevant.

Fill tank to ¼ full.

Dose with Sodium Hypochlorite solution to achieve 50 ppm (mg/litre) when tank full.

Continue refilling tank to overflow level, stirring water occasionally to achieve even distribution of chlorine within tank.

Test to ensure 50 ppm (mg/litre) of chlorine is present.

Leave to stand for 1 hour.

Open tank cold water down service(s) valves. Working successively away from the tank, each draw off fitting shall be opened until the discharge water smells of chlorine at which point the draw off fitting shall be closed leaving the system charged with the heavily chlorinated water.

The tank shall not be allowed to run dry during this operation nor shall the level of free chlorine drop below 30 ppm (mg/litre).

The entire system and tank shall remain charged with heavily chlorinated water for a further one hour when a sample shall be taken, and measured from the draw off point furthest from the tank.

If the concentration of free chlorine found above is less than 30 ppm (mg/litre) the system and tank shall be drained and the chlorination above repeated.

If the concentration of free chlorine found above is a minimum of 30 ppm (mg/litre) the tank and system shall remain charged with chlorinated water for a further 16 hours. The tank and system shall then be drained and flushed with clean water until residual chlorine at the drain off fittings is not greater than present in the water from the supply undertakers mains.



Fill system with clean water.

Note 1

Due regard to the Health and Safety of all building users must be considered when carrying out chlorination of pipework systems.

A work method system and full risk assessment must be carried out, agreed with the Premises Manager and written record made for Premises Health and Safety file prior to any work commencing.

Note 2




APPENDIX 3

Chlorination of Mains Water Services

The following is a specialist procedure and must be carried out by a competent contractor

The mains water system or part system should be flushed with clean water.

The mains water system or part system being treated shall have sodium hypochlorite added at the highest point of the system and drawn through each outlet and through a drain cock installed adjacent to the mains water isolating stopcock.

The system or part system shall be left filled with chlorine solution of 50 ppm (mg/litre) for a minimum of sixteen (16) hours.

The system or part system shall then be emptied and flushed with clean water until residual chlorine at the drain off fittings is no greater than that present in water from the supply undertakers mains.

Note 1

Due regard to the Health and Safety of all building users must be considered when carrying out chlorination of pipework systems.

A work method system and full risk assessment must be carried out, agreed with the Premises Manager and written record made for Premises Health and Safety file prior to any work commencing.

Note 2




KENT PROPERTY SERVICES - Contact the:

KPS Helpdesk: Tel: 0845 3000 346.

Kings Hill, West Malling




Documents

Reducing the risk of Legionella - Home - KELSI€¦ · Web viewThe Health and Safety Commission give practical guidance on the ... ( to be fitted with low level drain valve