Improved water conservation practices using rain water harvesting in the wet and intermediate zones of Sri Lanka

Abstract

Fresh water is a limited and precious resource that is often taken for granted. However many areas of the developing world suffer a lack of safe water. Therefore, water bome diseases account for an estimated 80% of all illnesses in developing countries. In addition, millions of women and children walk several kilometers every day just to fetch a minimum quantity of water for their families. Furthermore, the Sri Lankan government also faces many problems in finding safe water sources to meet the growing water needs of the entire population. Roof rainwater harvesting is the only feasible option in some parts of the country, to deal with this issue to a certain extent where no other water sources are available./ The research is targeted to study the water conservation practices using Rainwater Harvesting in the wet and intermediate zones of Sri Lanka. To analyze performance of a selected roof rainwater harvesting system, thirty years (1968-1998) of daily rainfall data from Galle, Rathnapura, and Kurunegala districts have been used. The roof sizes considered were 50 m2,75 m2, 100 m2 & 200 m2 and tank capacities considered were 1 m3, 2 m3, 5 m3 & 7.5 m3 for family size of five members. The daily water demand is taken as 120 liters per capita per day./ The results show that there is a 79% probability of success in the Galle district for supplying 300 liters of water per day per family (i.e. 50% demand fulfillment) by using a 5 m3 tank with a roof catchment area of 75 m2. The equivalent result for Rathnapura is 93% while for Kurunegala it is approximately 71%. Hence, the results clearly show that rainwater harvesting is an excellent alternative option for the partial fulfillment (50%) of daily domestic water demand within the wet and intermediate zones of Sri Lanka./ Finally, it can be concluded that roof rainwater harvesting is a very promising alternative solution for increasing water demand of the country. However, the research also shows that during a few months in the year, domestic users will be unable to survive comfortably only with rainwater harvesting.