'Let not a drop of water that falls from the sky flow into the sea.' These were the words of Parakramabahu, a 13th century Sri Lankan monarch, who constructed Parakrama Samudra or the Sea of Parakrama, a massive rainwater harvesting reservoir which to this day irrigates vast stretches of paddy fields in the Gal Oya district of Sri Lanka.
Rainwater harvesting is a technique of conservation wherein water is harvested from roof and ground catchments and then safely stored and treated as and when necessary. Archaeologists in Sri Lanka have discovered a whole network of storage reservoirs, pools, artificial streams and fountains in the north and central regions of the island country. In fact, it has also been an integral part of the irrigation system of the country.
A critical issue today is the supply of adequate water and disposal of the excess to meet society's needs and ensure equitable access throughout the year for urban and rural populations, flora, fauna and other living forms. Thus, it is important that rainwater be conserved, rather than left to flow down the drains or flood fields and low-lying areas.
The pioneering National Policy on Rainwater Harvesting (RWH) was introduced recently. It has been formulated by the RWH Secretariat comprising Ministry of Urban Development and Water Supply, the National Water Supply and Drainage Board and the Lanka Rain Water Harvesting Forum (LRWHF). The policy had been under revision and discussion since 2004.
"Sri Lanka is the first country in the world to have a national policy on rainwater harvesting," says Dinesh Guwardene, Minister of Urban Development and Sacred Area Development. According to Tanuja Ariyananda, Executive Director, LRWHF, the objectives of the new policy are in keeping with the increasing costs of pipe-borne water supply, drainage, flood control and soil conservation.
"The plan is to make rainwater harvesting mandatory. It will be introduced in stages in all municipal and urban council areas within a prescribed time period. It will initially cover certain categories of buildings and development projects and will also be promoted intensively in all council areas," elaborates Ariyananda.
The rationale for the policy is based on the fact that Sri Lanka today has an annual rainfall volume of about 5,900 cubic metres from which the annual discharge volume into the sea is about 1,400 cubic metres. It also ranks high in the world in the annual renewable quantity of water with two monsoons each year, explains Ariyanand. The rainfall volume, annually, from both monsoons ranges between 750 and 6,000 mm across the country. However, due to vagaries of the rain; improper land management practices such as unrestrained filling up of low lands and restriction of natural drainage paths; and due to insufficient storage mechanisms, a substantial amount of rainwater flows into the sea.
Therefore, the policy aims to upgrade the status of rainwater from a supplementary - which it is right now - to an optional source in all rural-based water supply projects.
Rainwater harvesting has a number of benefits. Besides minimizing the use of piped potable water for secondary purposes, it prevents depletion of ground water and reduces water stress during droughts and lower salinity intrusion.
It also reduces unproductive labor time and hazards, faced mainly by women and children in fetching water across a distance. "In our water and sanitation projects in Kalutara, where rain is plentiful almost the whole year round, local women displayed a keen interest in rainwater harvesting that would give them water in the house, instead of them having to fetch it even from a few meters away. We are now planning to get expertise from the RWH Forum," says Shirley Rodrigo, Executive Director of Water and Sanitation Decade Service.
But one of the major hurdles that has to be overcome in making rainwater harvesting popular is the traditional mindset that believes rainwater to be impure and not suitable for drinking. "There are safeguards such as using suitable roofing material to collect rainwater and collecting only the rainwater that falls after the first shower," explains Lionel Gunatilleke, a trustee of RWH forum.
Gunatilleke began rainwater harvesting as a hobby and successfully implemented it even before the forum was launched. "As we live on high ground, shortage of water used to become a serious problem during the dry months of March and April. I had to transport gallons of water in my car everyday. I was spending more than I could afford on car repairs. It was out of sheer necessity that I started exploring the possibility of rainwater harvesting. Now this experiment gives us water throughout the year and also enough for my wife to indulge in gardening," he says.
Quoting scientific research on the use of rainwater, Ariyananda has a word of caution, "There is one snag in using rainwater for drinking. It lacks minerals and users must make sure that they add it in their food if they depend totally on rainwater for drinking water."
Over the years, the LRWH Forum has conducted a number of workshops and held exhibitions to spread awareness. It has also provided on-the-job training to masons and given demonstrations in households on the operation and maintenance of rainwater harvesting systems. Links have been built, with both the government and the NGOs exchanging information and communicating through awareness programmes, but there are still a number of challenges that have to be met to optimize this abundant and free gift of nature.