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Overview of Global Trends in Rainwater Harvesting

Regional Southeast Asia Conference on

RAINWATER HARVESTING IN IWRM

November 25-26, 2008, Davao City, Philippines

Jessica C. Salas, Past President, IRCSAI

Greetings from IRCSA and the

Rainwater Partnership

• Contents of this Presentation:– Global Trend in Rainwater Harvesting– Examples of Rainwater Utilization Practices – Focus in South East Asia– Institutions in RWH Development & Advocacy– The Future of Rainwater Harvesting

Rainwater Utilization Trend among Developed Countries

• Integration in public water supply (dual or multi source water supply)

• Government Policies offer incentives & exact fees: subsidies, tax rebates, eco tax for processed water, sealing fee, required minimum storage based on covered area.

• Increasing commercialization

• Use in high-rise buildings

• Used for flood control and sustainable drainage

• A requirement for ground water recharge in sealed surface

• Recognized as effective tool for demand management

• Expected to impact on reduced investments in large water infrastructures

• Conducted studies on how RWH mitigate climate change

• Conducted studies on how RWH make communities adapt to climate change

Trend in Developing Countries• Primary source of water in some areas• World Health Organization set standards for

rainwater as drinking water• Some governments do not invest in rainwater

harvesting. Priorities are on centralized services for irrigation and drinking water.

• Low level of understanding of the ecological and economic impact of RWH

• Weak/absence of structural support such as legislation, service providers, credit, education, information dissemination, guidelines.

• Need for RWH integration in watershed management and IWRM

• Damaged ecosystems lead to depletion of water and land resources. Countries use man-made water storage to supplement natural storage of water.

• Some countries use RWH to re-condition soil caused by desertification.

• On-going studies on how RWH increase resiliency to weather impact of climate change.

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GLOBAL PRACTICES

RAINWATER HARVESTING

Japan, Miyake Island

• Trees are used to catch rainwater

• Rainwater, considered as celestial water, used for drinking and for brewing tea

• Tap water which is available, is only used for flushing toilets

• Population dislikes chemical in water

Tokyo, Japan

• Published guidelines for rainwater utilization.

• Assisted households and businesses in planning

• Local authorities were granted subsidies & interest-free loans

• Annual rainfall: 1,400 mm

Example: 1993. EDO Tokyo Museum with 2,500 m3 tank & roof area of 30,000 m2 used as catchments.

India

• Practiced both in cities & rural areas• Rooftop catchments & ground water recharge

are the most popular practices• Government Policies & Research support RWH• The ground water artificial recharge experiment

of the Central Groundwater Board showed:– Using check dams, resulted in a storage of 4,600 to

22,180 m3 & a rise of 0.8 to 9.9 m in water level, 9 to 30 hectares benefited

– Injection wells with roof rainwater resulted in a rise in water level by 0.51 m.

Taiwan

• Promotion of industrial/residential rainwater use began in 1996.

• Total investment– 50.73 million NT$

• Total storage capacity 20,538 tons

• Substituted water supply is 700,000 tons.

• Main uses: toilet flushing (84.1%), irrigation (8.8%), cleaning (5.5%), landscaping (1.3%)

Taiwan

Sub basin Planning for Flood Control

Agriculture

China

Before RWH• Yield/water consumption –

wheat: 0.4 to 0.5 kg/m3;

corn 1.7 to 2.0 kg/m3

• Farmers’ income >0.5USD

After RWH• Increase in yield/water

consumption - (wheat) 51.3 to 60.6%; 9.6 to 13.6% (corn)

• Increase in Yield of 20-88%

• 1.3 million with access to drinking water

• 2.2 million tanks built• 200,000 hectares of land

irrigated

Loess Plateau Annual Rainfall : 300-400 mm, No other water source

Rainwater Harvesting in Gansu, China

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Africa

Australia: Olympic Village Saving 55% of fresh water with RWH Annual Rainfall – 850 mm

Caribbean • Haiti- every

household and building use rainwater for non-potable use

• Barbados – A building code requires all residential building area 3,000 ft, a 6000gal capacity reservoir. Tax incentive $1,500 to $.50/gal of installed tank capacity

England• Annual Rainfall:• RWH Industry growth rate doubles every year for

the last 3 years.• Annual growth is £1,000,000 or US$1.8 M• Sustainable Building Strategy suggests a 25%

reduction in potable water use.• Planning Policy Guideline 25 proposes RWH to

reduce potential runoff & control flooding.• Example: London’s annual rainfall: 613 mm• Thames Water, its water supply company utilizes

55% of rainfall• Latest project is the Millennium Dome

Millennium DomeRoof Area, 100,000 m2 50 m high.

Satisfies 20%of 500 m3

requirement of toilets.

Belgium

1999 Code of Vlaamse Milieunaatschapij: all new and repaired houses to install rainwater facilities with minimum cistern capacity of 3,000 gal, using at least 50% of surface, and must have an overflow or seepage system. The law is supported with a financial grant.

.The University of Ghent has 136 apartments for students all using rainwater for toilets.

Leonard Bus Co., - for using rainwater for cleaning, savings of 2,000 m2 of fresh water

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Experiences in South East Asia

Bangladesh, Cambodia, Indonesia, Malaysia, Philippines, Singapore,

Thailand, Vietnam

Indonesia

• February 23, 2007 – State Ministry for the Environment & the Jakarta Administration made a call to promote rainwater harvesting.

• Annual Rainfall: 2,500 to 3,000 mm• Tsunami and earthquake victims in

Nias Island (711,000) population received rainwater harvesting facilities

Kaibolafin Village on Kola Island survive on a single catchment from a church roof & a single cistern.

www.irc.nl/pmt

Bangladesh

• RWH is not a way of life. • Massive distribution of wells and water pump.• After 40 years of massive ground water withdrawal in

the sedimentary soil, arsenic contamination of water was experienced.

• “The largest mass poisoning of a population in history… the scale of this environmental disaster is greater than any seen before.” A German Daily Newspaper

• 59 out of 64 districts are affected.

• We are happy to see that the government has put emphasis on the use of rainwater for which we have long been fighting for.” Chief, Dhaka Community Hospital

Singapore

• ¾ of the land is used as catchment for rainwater.

Study of rainwater from the Bedok Area says, water quality is comparable with water coming from a protected watershed.

Vietnam• Annual rainfall is 120 to 300 cm.• Sources of water: surface &

ground. Some rain collected during rainy season.

• Arsenic contamination of groundwater beginning to show.

• Rainwater jars and filtration system is the response to the situation (Country report on Drinking Water Quality)

• HANDS ON SAIGON built 100 tanks for women in Can Gio district.

• UNICEF conducts training on rainwater tank construction.

“Only rich people can afford rainwater tanks.”

Cambodia

• Annual Rainfall is 1,400 mm (central plain) & 3,800 mm (mountains)

• Widespread use of well water, high concentration of arsenic found.

• 85% of farmers rely on rain.

• Income of $1 a day

• Project of Engineers without Borders (EWB) – rainwater tank for 1,200 school children.

• Project of Oxfam: construction of 17 RWH pools & 29 canals

Thailand

• 1979, the Royal Govt declared a policy of water resources dev’t and jars and tank construction of drinking water started.

• Today, most households have 1 household tank and a membership in a community tank.

•After 10 years, 8 million tanks have been constructed. Private sector competition brought prices down but education lagged behind and incidence of diarrhea increased.

Philippines

• SWIP project (small water impounding project) started building RWH units in 2002.

• NGOs: (PCWSS) constructed ferro cement tanks in the islands of Tawi Tawi, Mindanao (2000)

(Kahublagan) conducts studies & projects in Capiz & Iloilo (since 1983)

• No gov’t policy to promote rainwater harvesting.• Private sector: Households & industries such as the

Cebu Export Processing Zone, banana plantations, resorts and hotels use rainwater harvesting.

LAO PDR

WSP Lao

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INSTITUTIONS FOR DEVELOPMENT & ADVOCACY

International Rainwater Catchment Systems Association With Regional Networks in1. North America2. Latin America & the Caribbean3. Europe4. South and East Africa5. Middle East6. South Asia7. East Asia8. Australia

Rainwater Partnership

• Based in UNEP

• IRCSA as a founding Partner

• 60 member-partners including country governments and UN agencies, and international NGOs

• Headed by an Advisory Council

THE FUTURE

Delphi Study conducted in Germany by 45 international water experts:

• Groundwater pollution will continue because of farming.

• Centralized public water will decrease its prominence because of cost

• Technology requisites for a new system with high degree of hygiene is existing now.

• Rainwater Utilization is socially acceptable backed up by a state of the art technology.

• 5 to 20% max. of households will be connected to a central process water system in 2010.

• Only 10% of the newly installed toilets will be using processed water.

• By 2020, it will be possible to build houses that are self sufficient in water usage.

“The future belongs to a decentralized

infrastructure which is flexible enough to adapt

to technical progress when environmental

policy, local conditions and/or individual needs

change.” Martin Bullerman

Member, Water Working Group Delphi Study

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Rainwater Harvesting

is the decentralized water technology

for the next millennium.

Thank You