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Resource guidelines for greywater use
and management
Dr Kirsty Carden, University of Cape Town
18 April 2016
Water Research Commission project K5/2592
Development of resource guidelines for greywater use and management
1 Agenda for workshop
1. Welcome and introductions
2. Background to project – status quo / definitions
3. Identification of thematic areas / issues to be addressed
4. Introduction to greywater resource guidelines
5. Way forward / closure
2 Strategic planning
“South Africa is a ‘water-stressed’ country, bordering on water scarce…water
may become a binding constraint on development, at least in some parts of
the country. There is a need for urgent attention to be given to the
management and conservation of water resources, especially in stressed
water catchments… Addressing supply and demand in the context of
unevenly distributed and variable resources is a matter of central importance
in national planning.” (National Planning Commission, 2011)
‘In many parts of the country, we are fast approaching the point at which all of
our easily accessible freshwater resources are fully utilised. All South Africans
must recognise this situation so that necessary steps are taken to assess
current and future demands for water. This will not be an easy task, but with
the necessary resolve to plan and implement the required interventions, a
secure water future can be achieved.’ – NWRS2, 2013, page 4
3 National surface water storage levels
http://niwis.dwa.gov.za/niwis2/SurfaceWaterStorage
4 Predicted total water withdrawals
(Source: Hedden, 2016)
5 Resilience-based water management
Blue water
Sector approach
dominated by
economics and
engineering,
emphasis on
supply
Integrated blue
water
An economic
approach to
freshwater
including
environmental
flows
Integrated blue
and green water
Adding land
interactions,
surface runoff and
infiltration to food,
energy, and
ecosystem
services
Green and blue
water with social
and ecological
interactions
Resilience based,
addressing the
need to sustain
rainfall, capture
resource value,
and cross scale
interactions and
feedbacks
IWRM /
IUWM
SuDS
WSUD
Evolution from the 1990s to present day realisation
Adapted from Rockstrom et al., 2014
6 Diversifying household water sources
Precipitation
Evapo-transpiration
Reduced
volumes of
runoff Increased
Infiltration
Reduced wastewater
discharge
Reduced Municipal potable
water demand
Stormwater
Harvesting
Rainwater
Harvesting
Groundwater
Greywater reuse
7
7
Household greywater - What is it?
Greywater is untreated wastewater from baths, showers,
kitchen and handwash basin, and laundry (i.e. household
wastewater excluding toilet waste)
Class 1: Bathroom greywater – showers, basins, baths
Class 2: Laundry greywater – laundry basins and washing
machines
Class 3: Kitchen greywater – kitchen sinks and dishwashing
machines
Only applies to serviced settlements
8 Greywater recycling
Source: Ana Delétic
9 Simple home-based greywater systems
Photos courtesy: Kevin Winter
10 Combined rain- and greywater harvesting
11 Greywater and food security
12 Greywater and food security (2)
Photos courtesy: Khanyisa Projects
13 Greywater tower gardens
14 Draft National Sanitation Policy (2016)
15
16 Quality issues
17 Greywater management in informal settlements
18 Greywater management in informal settlements
19 Timeline of greywater research
20 Project aims
Address (and mitigate) the risks associated with the management and use of domestic greywater, and support the wider uptake of this practice in South Africa, in order to realise diverse benefits such as:
• building resilience into the water supply system;
• managing water demand;
• reducing volumes of greywater to wastewater systems;
• reducing diffuse pollution loads from un-serviced settlements
21 Technical background report
• Definition of terms and concepts
• Role of greywater management in water supply and
food security
• Applicable regulations / policy / guidelines on
greywater use and management
• Existing greywater use and management systems
• Recommendations for sustainable greywater use
and management
22 Greywater guidelines
• Greywater quantity / quality and fitness for use /
application
• Managing risks and uncertainty in greywater use /
reuse
• Use of greywater to supplement irrigation activities
• Greywater management options, including:
treatment, disposal and reuse
• Planning for (municipal) programme implementation
23 Method
• Compile relevant research findings
• Survey greywater system users at household scale
• Local and national stakeholder workshops
• Review of legislative and health aspects
• Focus group discussions
• Develop guidelines, including simple ‘operations and
maintenance’ information, as well as strategic
technical background document
24 Thematic areas to be addressed
• Health aspects
• Legislative issues
• Risk management / quantification
• Socio-cultural issues
• Appropriate applications / uses
• Key design considerations
25 Health aspects
• Is greywater a health risk?
• What are the pathways to infection?
• What preventative barriers are there?
• What about treatment options?
• Is hygiene education important?
Health aspects of re-use of household
wastewater (greywater)
Dr Jo M Barnes Division of Community Health
Faculty of Health Sciences
University of Stellenbosch
TYGERBERG
27 Household greywater - What is in it?
• Soaps, detergents, fabric softeners
• Hair products (shampoo, hair conditioner)
• Toothpaste
• Medicines
• Disinfectants
• Pesticides
• Dyes
• Cosmetics
• Lint and other fibres
• Food particles as well as fats, oils, blood
• Human waste products: saliva, sweat, body oils, hair,
blood, and some urine and faecal matter
28
28
Greywater is NOT a “safe” substance
• Contains bacteria, viruses, parasites - pathogens able to
cause disease in humans or animals
• Species and total counts vary widely according to climatic
conditions, season, sanitation technology available,
sanitation habits of the people living in the dwelling and the
disease incidences in the area
• Potential re-use of greywater is as much a public health
issue as it is a water conservation priority
Implementation involves balancing risks
29
29
International restrictions on re-use (1)
• Water used to wash articles contaminated with faeces should not
be used
• Greywater should not be allowed to leave the boundaries of the
property and should under no circumstances be allowed to enter
the stormwater system
• Provision must be made for the safe disposal of excess
greywater into the sewage system during rainfall or when too
much greywater is produced for the garden to absorb
• Greywater should never be allowed to pond or pool where
mosquitoes can breed or where it can develop foul smell
• “Fail-safe" disposal system required – PRECAUTIONARY
PRINCIPLE to be applied
30
30
International restrictions on re-use (2)
• Never apply to edible crops
• Withhold from areas where children play, such as lawns – as
children are highest risk group for acquiring infection.
• Withhold if anybody living on the premises is suffering from
diarrhoea, ear or skin infections, etc.
• Warm water should be stored in a holding tank to cool down.
Use within 24 hours; otherwise the bacterial load will rise too
high for safety.
• Everybody living on the premises where gardens are irrigated
with greywater should wash their hands without fail before
eating or drinking.
31
31
Realities in developing countries
• Far larger proportion of population poverty-stricken
• Burdens of disease predominated by infectious diseases
• 40% of women aged 25 - 35 HIV+ in South Africa
• Very poor sanitation - high infection pressure
• Direct link between food and contaminated water
• Populations more inclined towards 'civil disobedience' due to
lack of enforcement of regulations
32 Who is most at risk of water-related disease?
• Newborns, babies and children
• Pregnant women and their developing foetuses
• Old people
• Individuals with compromised immunity such as those with TB, HIV/AIDS
• Persons who are chronically malnourished
• Patients on long-term medication
• Persons with pre-existing chronic diseases such as diabetes, kidney failure, liver failure
• Persons who abuse alcohol or other drugs
= Large proportion of SA population
33
33
Risks related to irrigating edible crops
• Never apply directly to edible crops - especially not to vegetables eaten raw or lightly cooked, such as in salads
• Avoid for root crops such as carrots, since pathogens accumulate in the topsoil and in the roots
• Irrigation carried out under plastic sheeting or buried under the
soil surface significantly reduces crop risks, but microbial
contamination still persists
• Survival of E. coli O157:H7 was greatest in soil under rooted
grass - moderate decline occurred only after 130 days.
Edible crops should only be irrigated with greywater when risk of
disease becomes less than the risk of hunger.
34
34
Reuse of greywater already happens
Different liability when officially sanctioned - when
initiated by citizens themselves they carry the risk
35
35
Greywater systems - problems increase risks
• High levels of commitment and sophisticated understanding
• Strict supervision - luxury in developing countries
• Proper, safe systems (filters, directional valves, etc.)
• During outbreaks or health hazards, how can use be stopped?
(No 'undo button')
• What if subsequent owners do not comply with safety rules?
• Who will carry costs if health risks rise to unacceptable levels or
outbreaks occur?
• If stopped, who will compensate the poor who make a living
selling the produce grown with greywater?
36 Legislative issues
• What legislation is relevant?
• How important is a legislative framework?
• Should legislation be developed?
• What about enforcement?
• Are there any relevant building codes?
• What about plumbing ‘sign-off’ on home-based
systems?
Legislative review
Dr C Young
Department of Private Law
University of Cape Town
CONSTITUTION
NATIONAL WATER ACT
WATER SERVICES ACT
REGULATIONS
STRATEGIES/POLICIES/GUIDELINES
CONSTITUTION OF THE REPUBLIC OF SOUTH AFRICA, 1996
S 27 • Everyone has the right of access to water • Sanitation?
NATIONAL WATER ACT
No mention of grey water specifically
Preamble: “water is a scarce and unevenly distributed national resource which occurs in many different forms which are all part of a unitary, interdependent cycle” “the ultimate aim of water resource management is to achieve the sustainable use of water for the benefit of all users” “the need for the integrated management of all aspects of water resources”
S 2 read with s 3: water must be used, protected, developed, conserved, controlled and managed in such a way as to promote “the efficient, sustainable and beneficial use of water in the public interest”
NATIONAL WATER ACT
S 38 of the NWA: Specific authorization Reuse of water for the purposes of irrigation of land - waste water generated by industrial activities / waterwork
Revision of General Authorisations in terms of section 39: GN 665 of 6 September 2013: Government Gazette No. 36820]: Disposal and re-use of waste water Reference to “grey water”: Disposal to an onsite facility and the permission to reuse domestic wastewater Grey water definition: “wastewater generated through domestic activities and premises, including washing, bathing and food preparation, but does not contain sewage” No explicit guidelines
The Regulations Relating to Compulsory National Standards and Measures to Conserve Water (GNR.509 of 8 June 2001): disposal of grey water: WSI empowered to provide the limitations for the use of grey water where use will have negative impact of the environment, health or other water resources Grey water is defined as “waste water resulting from the use of water for domestic purposes, but does not include human excreta” Grey water included within the definition of “effluent” = permissible to use effluent upon approval from WSI The obligation falls on the WSI to ensure that use of such effluent does not pose a health risk, prior to approval of this use Where effluent or non-potable water, including grey water, is accessible via a tap, a sign must be clearly and permanently displayed that states that the water is non-potable.
WATER SERVICES ACT
No mention of grey water specifically
The Draft National Sanitation Policy (GN 70 of 12 February 2016: Government Gazette No 39688)
Grey water defined as “wastewater resulting from the use of water for domestic purposes, but does not include human excreta” Policy approach to grey water:
Proper management, storage and treatment of grey water required because of potential health implications Reuse of grey water important to alleviate pressures on demand for water resources Minister will develop regulations for the “use, re-use recycling and recovery of the liquid, solid and gaseous constituents of human wastewater and excreta”
WSA’s responsible for ensuring that national grey water guidelines are adhered to, and DWA monitors this adherence. BUT: no enforcement mechanism to ensure compliance!
OTHER LEGISLATION?
Publication of the Environmental Impact Assessment Guideline for Aquaculture in South Africa
• Encourages the use of grey water for irrigation of landscapes
• Water “generated by washing and other non-sewerage activities”
Environmental Impact Assessment Guideline for Renewable Projects
• Encourages consideration of the use of grey water = mitigating environmental impacts in the context of biomass energy projects
Application of the National Building Regulations (SANS 10400-Q: 2011, Third Edition)
• “domestic waste water excluding toilet water” • Grey water must be disposed of in a separate system to a
ventilated pit toilet
National Environmental Health Norms and Standards for Premises and Acceptable Monitoring Standards for Environmental Health Practitioners (GN 1229 of 24 December 2015: Government Gazette No. 39561 (National Heath Act)
• “Refers to waste water that does not contain significant amounts of faecal pollution (i.e. not sewage discharges). Typically, it consists of water discharged from baths, showers and/or sinks”
OTHER LEGISLATION
Standards For Health Related Water Quality Management On Premises
• Safe water = “water that has been tested and does not present any significant risk to health over a lifetime of consumption (microbiological, physical and chemical quality)”
• Standards are provided for use of grey water: • Use = flushing of toilets/irrigation • NOT for drinking, cooking, personal hygiene • Grey water created from laundry, dishwashing and bathing = recycled prior
to use for irrigation / constructed wetlands. • Disposal = safe • Education of users and communities is required in terms of the health and
hygiene implications of the use thereof. • Any use of grey water should be subject to prior approval being obtained
from WSI • WSI should consult with an Environmental Health Practitioner prior to
granting any approval = EHP should test the effluent for compliance monitoring purposes.
• Any point at which the grey water could be accessed must be clearly marked indicating the presence of effluent and its non-potability.
• Cross-connection of systems cautioned against - avoid contamination of potable water
MUNICIPALITIES WITH BYLAWS
Western Cape City of Cape Town Metropolitan Municipality Drakenstein Local Municipality Bitou Local Municipality George Local Municipality Hessequa Local Municipality Knysna Local Municipality Mossel Bay Local Municipality Overstrand Local Municipality Swellendam Local Municipality Theewaterskloof Local Municipality West Coast District Municipality Bergriver Local Municipality Saldhana Bay Local Municipality Swartland Local Municipality Cederberg Local Municipality Breede Valley Local Municipality
Gauteng
Kungwini Local Municipality Mogale City Local Municipality
North-West Madibeng Local Municipality Moses Kotane Local Municipality Moretele Local Municipality Ramotshere Moiloa Local Municipality
Eastern Cape Buffalo City Local Municipality Ntabankulu Local Municipality Nelson Mandela Metropolitan Municipality Joe Gqabi District Municipality
Mpumalanga Thaba Chweu Local Municipality KwaZulu Natal
Umzimkhulu Local Municipality Umhlathuze Local Municipality uThungulu District Municipality
Limpopo Vhembe District Municipality Mogalakwena Local Municipality Greater Sekhukhune District Municipality
MUNICIPALITIES WITHOUT BYLAWS
Western Cape Cape Winelands District Municipality Central Karoo District Municipality Eden District Municipality Overberg District Municipality Breede River/ Winelands Local Municipality Langeberg Local Municipality Stellenbosch Local Municipality Witzenberg Local Municipality Beaufort West Local Municipality Laingsburg Local Municipality Prince Albert Local Municipality Kannaland Local Municipality Oudtshoorn Local Municipality Cape Aghulas Local Municipality Cederberg Local Municipality Matzikama Local Municipality
Gauteng City of Johannesburg Metropolitan Municipality City of Tswane Metropolitan Municipality Ekurhuleni Metropolitan Municipality Metsweding District Municipality Sedibeng District Municipality West Rand Distric Municipality Emfuleni Local Municipality Lesedi Local Municipality Midvaal Local Municipality Merafong Local Municipality Randfontein Local Municipality Westonaria Local Municipality
North-West Bonjanala District Municipality Dr Kenneth Kaunda District Municipality Dr Ruth Segomotsi District Municipality Ngaka Modiri Molema District Municipality Kgetlengrivier Local Municipality Rustenberg Local Municipality Maquassi Hills Local Municipality Matlosana Local Municipality Tlokwe Local Municipality Ventersdorp Local Municipality Greater Taung Local Municipality Kagisano-Molopo Local Municipality Lekwe-Teemane Local Municipality Mamusa Local Municipality Molopo Local Municipality Naledi Local Municipality Ditsobotla Local Municipality Mafikeng Local Municipality Ratlou Local Municipality Tswaing Local Municipality
Mpumalanga Ehlanzeni District Municipality Gert Sibane District Municipality Nkangala District Municipality Bushbuckridge Local Municipality Mbombela Local Municipality Nkomazi Local Municipality Umjindi Local Municipality Albert Luthuli Local Municipality Dipaleseng Local Municipality Govan Mbeki Local Municipality Msukaligwa Local Municipality Pixley Ka Seme Local Municipality Dr JS Moroka Local Municipality Emakhazeni Local Municipality Emahaleni Local Municipality Steve Tshwete Local Municipality Thembisile Hani Local Municipality Victor Khanye Local Municipality
MUNICIPALITIES WITHOUT BYLAWS
Northern Cape Frances Baard District Municipality, John Taolo Gaetsewe District Municipality, Namakwa District Municipality Pixley ka Seme District Municipality, Siyanda District Municipality, Dikgatlong Local Municipality, Magareng Local Municipality, Phokwane Local Municipality, Sol Plaatje Local Municipality, Gamagara Local Municipality, Ga-Segonyana Local Municipality, Joe Morolong Local Municipality Hantam Local Municipality, Kamiesberg Local Municipality Karoo Hoogland Local Municipality, Khai-Ma Local Municipality Nama-Khoi Local Municipality, Richtersveld Local Municipality Emthanjeni Local Municipality, Siyancuma Local Municipality Siyathema Local Municipality,Thembelihle Local Municipality Ubuntu Local Municipality Umsobomvu Local Municipality Khara Hais Local Municipality Kgatelopele Local Municipality Tsantsabane Local Municipality Kai! Garib Local Municipality
Free State Fezile Dabi District Municipality Lejweleputswa District Municipality Motheo District Municipality Thabo Mofutsanyane District Municipality Xhariep District Municipality Mafube Local Municipality Metsimaholo Local Municipality Moquaka Local Municipality Ngwathe Local Municipality Masilonyana Local Municipality Mtjhabeng Local Municipality Nala Local Municipality Tswelopele Local Municipality Mangaung Local Municipality Mantsopa Local Municipality Naledi Local Municipality Dihlabeng Local Municipality Maluti a Phofung Local Municipality Nketoana Local Municipality Phumelela Local Municipality Setsoto Local Municipality Kopanong Local Municipality Letsemeng Local Municipality Mohokare Local Municipality
Limpopo Bohlabela District Municipality, Capricon District Municipality Mopani District Municipality, Waterberg District Municipality Aganang Local Municipality, Blouberg Local Municipality Lepelle-Nkumpi Local Municipality, Molemole Local Municipality, Polokwane Local Municipality, Elias Motsoaledi Local Municipality, Ephraim Mogale Local Municipality, Fetakgomo Local Municipality, Greater Tubatse Local Municipality Makhuduthmanga Local Municipality, Ba-Phalaborwa Local Municipality Greater Giyani Local Municipality, Greater Letaba Local Municipality, Greater Tzaneen Local Municipality, Maruleng Local Municipality, Makhado Local Municipality, Musina Local Municipality, Mutale Local Municipality, Thulamela Local Municipality, Bela-Bela Local Municipality, Lephalale Local Municipality, Modimolle Local Municipality, Mookgophong Local Municipality, Thabazimbi Local Municipality
MUNICIPALITIES WITHOUT BYLAWS
KwaZUlu Natal eThekwini Amajuba District Municipality, iLembe District Municipality, Sisonke District Municipality Ugu District Municipality, Umgungundlovu District Municipality, Umkhanyakude District Municipality, Umzinyathi District Municipality, Uthukela District Municipality Zululand District Municipality, eMadlangeni Local Municipality, Dannhauser Local Municipality Newcastle Local Municipality, KwaDakuza Local Municipality Mandeni Local Municipality, Maphumolo Local Municipality, Ndwedwe Local Municipality Greater Kokstad Local Municipality, Ingwe Local Municipality, Kwa Sani Local Municipality Ubuhlebezwe Local Municipality, Ezinqoleni Local Municipality, Hibiscus Local Municipality Umdoni Local Municipality, uMuziwabantu Local Municipality, Umzumbe Local Municipality Vulamehlo Local Municipality, Imendle Local Municipality,, Mkhambathini Local Municipality Msunduzi Local Municipality, Mpofana Local Municipality, Richmond Local Municipality uMngeni Local Municipality, uMshwati Local Municipality, Big Five False Bay Local Municipality Hlabisa Local Municipality, Jozini Local Municipality, Mtubatuba Local Municipality Umhlabuyalinga Local Municipality, Emdumeni Local Municipality, Msinga Local Municipality Nquthu Local Municipality, Emnambithi-Ladysmith Local Municipality, Imbabazane Local Municipality, Indaka Local Municipality, Okhahlamba Local Municipality, Umtshezi Local Municipality, Mthonjaneni Local Municipality, Nkandla Local Municipality Ntambanana Local Municipality, Umfolozi Local Municipality, Umlalazi Local Municipality Abaqulusi Local Municipality, Ulundi Local Municipality, uPhongolo Local Municipality eDumbe Local Municipality, Nongoma Local Municipality
Eastern Cape Alfred Nzo District Municipality, Amatole District Municipality, Cacadu District Municipality Chris Hani District Municipality, O.R Tambo District Municipality, Alfred Nzo Local Municipality, Matatiele Local Municipality, Umzimvubu Local Municipality Amahlathi Local Municipality, Great Kei Local Municipality, Mbashe Local Municipality Mnquma Local Municipality, Ngqushwa Local Municipality, Nkonkobe Local Municipality Nxuba Local Municipality, Baviaans Local Municipality, Blue Crane Route Local Municipality Camdeboo Local Municipality, Ikwezi Local Municipality, Kouga Local Municipality Koukamma Local Municipality, Makana Local Municipality, Ndlambe Local Municipality Sunday’s River Local Municipality, Emalaheni Local Municipality, Engcobo Local Municipality Lukanji Local Municipality, Inkwanca Local Municipality, Intsika Local Municipality Inxuba Yethemba Local Municipality, Sakhisizwe Local Municipality, Tsolwana Local Municipality, Elundini Local Municipality, Gariep Local Municipality, Maletswai Local Municipality, Senqu Local Municipality, Ingquza Local Municipality King Sabata Dalindyebo Local Municipality, Mbizana Local Municipality Mhlonto Local Municipality, Nyandeni Local Municipality, Port St Johns Local Municipality
THEMES IN MUNICIPAL BYLAWS
Written permission required City of Cape Town, Drakenstein, Bitou, George, Hessequa, Knysna, Mossel Bay, Swellendam , West Coast, Bergriver, Saldhana Bay, Swartland, Cederberg, Breede Valley, Buffalo City
Excludes kitchen water Drakenstein
Excludes water from garbage grinder
Bitou
“Any device which entails the recycling or re-use of water shall not make use of water derived from any kitchen, excluding clothes washing machines, or from toilet discharges”
Madibeng, Moses Kotane, Moretele, Thaba Chweu, Greater Sekhukhune, Umzimkhulu, uThungulu, Ntabankulu
Only a definition provided Vhembe, Mogalakwena, Kungwini
No cross-connection Umhlathuze
Planning for low-cost housing to include access to grey water systems for irrigation
Mogale City
50 Risk Management / Quantification
• Why have previous guidelines not been widely
adopted?
• Are guidelines useful for managing risk?
• Is the WHO approach to risk management useful?
• What are the simplest ways to manage risk?
• Is a “Greywater Harvesting Assessment tool” a good
idea in principle?
52 Overview
• We know greywater can be dangerous
• Microbiologically, chemically
• SA Water Quality Guidelines
• Old
• Generalised
• Relevance?
• New approaches to risk management
• DALY
• Is it easily understood?
• What parameters should we focus on
• Environmental
• Legal implications
53 Varying quality of greywater
Reference Eriksson
et al., 2003 Rose et al., 1991 Cassanova et
al., 2001
Source Composite Shower Laundry
wash
Laundry
rinse
Composite Composite
Concentration
(mg/ℓ unless
otherwise stated)
Range Range Range
Faecal coliforms
(CFU/100ml)
6.0×103 126 25 1.82×104-
7.98×108
5.63×105
Faecal Streptococci
(Enterococci)
(CFU/100ml)
2.38×102
E. coli
(CFU/100ml)
<100-2800
For formal fully serviced residential houses – greywater in informal settlements will
have very different characteristics
54 SAWQG – Whats an appropriate standard?
According to the South African Water Quality Guidelines (DWAF, 1996), gastro-intestinal
and other illnesses can be expected to rise when people are in contact with E. coli
counts above 400 counts / 100 mℓ
55 Managing risk internationally
• WHO –
• Australian guidelines for
water recycling
56 Can it work in SA?
• What does a DALY mean?
• The disability-adjusted life year (DALY) is a measure of
overall disease burden, expressed as the number of
years lost due to ill-health, disability or early death. It
was developed in the 1990s as a way of comparing the
overall health and life expectancy of different countries.
57 Can it work in SA?
• Typical reference microorganisms used by WHO
include:
• Campylobacter - bacteria
• Rotavirus - viruses
• Cryptosporidium parvum - protozoa and helminths
• Some studies have used E.coli as a reference micro-
organism for bacteria – Howard et al.
58 Greywater Harvesting Assessment Tool
𝐺𝑊𝑅𝑅 = 𝑀𝐴𝑋 𝑈𝑇𝑅 − 𝑇𝑅𝑅𝑆1 + 𝑇𝑅𝑅𝑆𝑛 + …
59 Socio-cultural issues
• Are socio-cultural-religious considerations
important? Education also
• What are the most important socio-cultural
concerns? Desirability of greywater use
• Who / what are the most important ‘influencers’ of
social acceptance? Community leaders, churches, entrepreneurs
• Who are appropriate users? Those who demand it
• What are the likely behavioural impacts?
60 Appropriate applications / uses
• What are appropriate uses? Garden, toilet, car wash
• What are inappropriate uses? Depends on class and source
• Is scale important when designing a greywater
system? Yes, retention time
• How do you decide which risk preventative barriers
to adopt?
• Is greywater harvesting appropriate in both serviced
and un-serviced settlements? Risk prevention very difficult in
unserviced areas
61 Key design considerations
• What are the key technical design considerations? Include
overflow to sewer, ease of use, minimal O&M
• Centralised or decentralised systems; i.e. scale?
• Are there basic handling rules for greywater?
• What are the operation and maintenance issues; e.g. signage and labelling? Registration/licensing of system installers,
responsibility of home-owner, sign-off of home systems on transfer
• Is economic viability important? Also about making water available
for fit-for-purpose uses during times of water scarcity
• Are there potential impacts on other water services?
62 Greywater resource guidelines
1. Introduction to greywater harvesting
• What is greywater?
• Why harvest greywater?
• Appropriate (and inappropriate) uses
• General rules for harvesting greywater
• Greywater harvesting techniques – bucketing, diversion devices, treatment systems
2. Calculating volumes and demand
3. Legal considerations
4. Health risks associated with greywater harvesting
5. Installation, signage and labelling best practice
63 Greywater uses
