The field study will investigate the importance of Rain Water Harvesting (RWH) as a water
supply option. How can sustainable innovative solutions be developed to solve the water
problem of Sri Lanka?
Suffering from more than 30 years of civil war and damages after being struck by the tsunami
2004, Sri Lanka faces many challenges to recover and rebuilt the country. The access to water
is the most important need for a civilization´s existence. In the dry zones of the island people
suffer from long drought periods with dried up wells and no natural sources for water.
However the rainfall during the monsoon, even in these areas, is more than enough to provide
the water needs if properly collected, thus the run-off coefficient is more than 60%. Several
projects with rain water harvesting in so called RWH systems have been implemented with
success. Because these areas are not covered by the water supply net and therefore have no
tap water, the people are very positive to having the RWH system.
In the wet zones and especially in the urban environment of Colombo the situation is
different. Here most of the people have treated pipe-borne tap water. The metered tap water is
highly subsidized by the government which makes the cost low for the users and increases the
water consumption. The citizens do not feel a responsibility to be careful with resources since
the common opinion is that water is a never ending source. The majority of the households
find no reasons for installing a RWH system because it´s low economic profits. Even if there
is a legislation that demands all new buildings should have a RWH system not many
households have installed these systems. However the cost to deliver and treat this water is
very expensive for the government and demands a lot of energy. Huge investments need to be
done in both the treatment plants and the pipe-line net to meet the growing population in
Colombo area. Another problem is that 40% of the households today in Colombo have no
sewage connection but lead their wastewater directly or after a septic tank into the ground or
the sea.
If the awareness regarding these concerns could be improved and the conditions between tap
water costs and RWH be adjusted with changes in the subsidized system, a sustainable
solution to the water situation in Colombo with both economic and environmental benefits
could be found.
The result from the case study is a recommendation about installing RWH as a complimentary
source of water for the households. And investments in RWH systems should be focused to
industries, hospitals, schools, municipal buildings and other public buildings with a high
water demand and with the best possibilities for optimal results.
Further the case study treats a sustainable solution to the sewage situation. It shows the
Decentralized waste water treatment plant (DWWT) and its advantages.