Submission to UNEP GMEF: Rainwater Harvesting for the Global Ministerial Environment
Forum of UNEP
Description of Initiative:
Rainwater Harvesting is a popular term used for a tradition of collecting rainwater,
improved by modern concepts and technologies, a result of more than two decades
of research work around the globe. Today, Rainwater Harvesting is used in wet
and dry countries, in poor and modern situations, for water supply and for sanitation
in homes. It is utilized in addressing agricultural productivity and food security
for poverty alleviation, even in places with 200 mm of rain. Rainwater Harvesting
is employed in flood mitigation in rain-drenched countries, and in solving infiltration
problems of sealed surfaces in urban areas and industrial complexes, or in avoiding
polluted water and toxic ground water.
Most of all, Rainwater Harvesting, or RWH is environmentally sound as it assists
in recharging ground water, enhances wetlands, assists forest conservation, encourages
ecological farming, and slows down construction of new dams for water supply thus
helping the ecological flow.
Discussions during the 3rd World Water Forum session on Rainwater Harvesting are
1. On Water Supply and Sanitation
- In the face of water scarcity, another major option for water supply should
be considered at par with surface water and ground water. This third option is
Rainwater Harvesting. In some areas of the world, rainwater could be the only
option. This was shown by cases presented from Africa, South Asia, and the arid
and semi-arid regions of Brazil, Nepal, Sri Lanka, Thailand, and others.
- Rainwater quality can be improved to WHO standards with proper monitoring
and maintenance, and by using improved technologies. In South Australia, 42% of
the population drink rainwater and only 40% drink from the main water supply.
- In view of the above, the Forum recommended that RWH should be recognized
by the United Nations as a major option for water supply for health and sanitation.
Governments should issue guidelines and policies for water quality monitoring
and use of improved technology. A mix of technologies is appropriate in many situations.
2. On Water and Poverty Alleviation
- China reported that 5 million people relying on 300-400 mm annual rainfall
were benefited significantly by the practice of RWH. Additional examples were
presented from India. Forum participants agreed that rainwater harvesting is a
cost effective means to irrigate farms. It controls erosion, conditions soil,
helps recharge ground water and beneficially modifies farming practices.
- The participants recommended that RWH should be recognized as a basic strategy
for poverty alleviation. Governments should invest in RWH facilities.
3. On Urban Use
- Many mega-cities suffer from problems brought about by increased water demand,
intense pollution and the absence of an efficient drainage system.
- In Tokyo, RWH was advocated for water supply and disaster preparedness and
- In Bangladesh, 80 million people could have been affected by arsenic poisoning
from ground water, if not for the implementation of RWH.
- The problem of flooding in cities could be mitigated by RWH using low-impact
runoff retardation. The Water Resource Bureau of Taiwan reports the effectiveness
and the technology of such use.
- In Germany, 50,000 new RWH systems are installed every year to add to an
existing 500,000 systems, as reported by RWH equipment manufacturers.
Introducing rainwater harvesting in the country’s policy often starts
with an information campaign about the new concepts and technologies and good
practices around the world. When acceptability is seen, an ordinance is passed
requiring all building constructions to include RWH facilities. Incentives such
as tax rebates are offered if the owner adds a RWH system to an existing building.
These practices are found in Texas, Hawaii, Caribbean islands, Australia, Germany
and other European countries. Guidelines are issued and made accessible to the
public. Water quality monitoring guidelines are also issued. In one province in
the Philippines, a revolving fund was started to enable households to install
their own RWH facilities. In another province, a water concessionaire leads a
RWH campaign as its means of expanding its water installations. In Kenya, the
women contribute some amount every week to allow one RWH per member until all
women have their own tank.
The financial cost of rainwater varies across the globe, but it is invariably
lower than the alternatives. For example, in Lebanon it is $0.05 to $0.30 per
m3 of collected water, in Rajasthan, India, it is $0.02 to $0.06 per
liter. Essentially, the cost varies depending on the expenditure needed for construction
of the system. In Bangladesh it is $0.02 per liter of water, and in Malaysia it
is approximately $0.65 per m3 of water. In the Philippines it is $0.05/ liter,
and in Africa it is in the region of $0.09 per stored liter of water, including
Replicating the Initiative
The International Rainwater Catchment Systems Association (IRCSA) has documented,
through its 11 biennial international conferences, country experiences showing
replications, variations and patterns of rainwater catchment systems as adapted
to specific conditions in 8 IRCSA regions of the world. .
During the development years, IRCSA members – volunteer scientists and
development practitioners, were so focused with their studies and action researches,
that promotion has been relegated to the background. However, it could be said
that the proper time has come, since the world is experiencing water scarcity
and environmental degradation. Rainwater Catchment Systems or Rainwater Harvesting
technologies are appropriate for the prevailing conditions and are ready for the
to main news page