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 2. Background to project – status quo 3. Introduction to greywater harvesting assessment tool 4. Identification of thematic areas / issues to be addressed 5. Way forward 6. 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 Water security issues
4 Predicted total water withdrawals (Source: Hedden, 2016)
5 Resilience-based water management Evolution from the 1990s to present day realisation WSUD SuDS Green and blue water with social IWRM / and ecological IUWM interactions Integrated blue and green water Integrated blue Resilience based, Blue water water addressing the Adding land need to sustain interactions, An economic Sector approach surface runoff and rainfall, capture dominated by approach to infiltration to food, resource value, economics and freshwater and cross scale energy, and engineering, including interactions and ecosystem emphasis on environmental feedbacks services flows supply Adapted from Rockstrom et al., 2014
6 Diversifying household water sources Precipitation Evapo-transpiration Rainwater Harvesting Groundwater Reduced volumes of runoff Greywater reuse Increased Reduced Municipal potable Infiltration water demand Stormwater Reduced wastewater Harvesting discharge
7 Greywater recycling Source: Ana Delétic
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9 Household greywater system Image from http://www.waterrhapsody.co.za
10 Simple home-based greywater systems Photos courtesy of Kevin Winter
11 Combined rain- and greywater harvesting
12 Greywater irrigation in rural areas
13 Greywater tower gardens
14 Draft National Sanitation Policy (2016)
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16 Quality issues
17 Greywater management in informal settlements
18 Greywater management in informal settlements
19 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
20 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
21 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
22 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 guideline document, including a simple ‘operations and maintenance’ manual, as well as the strategic technical background document
Quantifying risk in a guideline Lloyd Fisher-Jeffes Greywater harvesting Workshop 1 18 April 2016 www.wsud.co.za
24 Overview • We know greywater can be dangerous • Micobiologically • 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
25 Varying Quality of greywater Reference Eriksson Rose et al ., 1991 Cassanova et et al ., 2003 al., 2001 Source Composite Shower Laundry Laundry Composite Composite wash rinse Concentration Range Range Range (mg/ℓ unless otherwise stated) 6.0 × 10 3 126 1.82 × 10 4 - 5.63 × 10 5 Faecal coliforms 25 (CFU/100ml) 7.98 × 10 8 2.38 × 10 2 Faecal Streptococci (Enterococci) (CFU/100ml) E. coli <100-2800 (CFU/100ml) For formal fully serviced residential houses – greywater in informal settlements will have very different characteristics
SAWQG – Whats an appropriate standard? 26 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
27 Managing risk internationally • WHO – • Australian guidelines for water recycling
28 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.
29 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.
30 Greywater Harvesting Assessment Tool 𝐻𝑋𝑆𝑆 = 𝑁𝐵𝑌 𝑉𝑈𝑆 − 𝑈𝑆𝑆𝑇 1 + 𝑈𝑆𝑆𝑇 𝑜 + …
Thematic mapping session Kirsty Carden Greywater harvesting Workshop 1 18 April 2016 www.wsud.co.za
32 Timeline of greywater research
33 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?
34 Socio-cultural issues • Are socio-cultural-religious considerations important? • What are the most important socio-cultural concerns? • What are the most important ‘influencers’ of social acceptance? • Who are appropriate users? • What are the likely behavioural impacts?
35 Appropriate applications / uses • What are appropriate uses? • What are inappropriate uses? • Is scale important when designing a greywater system? • How do you decide which risk preventative barriers to adopt? • Is greywater harvesting appropriate in both serviced and un-serviced settlements?
36 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?
37 Key design considerations • What are the key technical design considerations? • Centralised or decentralised systems; i.e. scale? • Are there specific considerations related to quantity and quality? • Are there basic handling rules for greywater? • What are the operation and maintenance issues? • Is economic viability important? • Are there potential impacts on other water services?
38 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 the “Greywater Harvesting Assessment tool” a good idea in principle?
Thank you To add to the debate go to www.wsud.co.za
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