Analysis and design of household rainwater catchment systems for rural Rwanda

Abstract

The Dian Fossey Gorilla Fund International (DFGFI) contacted MIT in September 2006 for technical assistance to analyze the water-supply potential within the Bisate Sector, Musanze District, Rwanda. The present study focuses on designing low-cost household rainwater catchment systems to improve the quantity and quality of water available and therefore achieve higher standards of living for the Bisate village. Given the climatic and geographic characteristics of Bisate, rainwater harvesting represents one of the most appropriate solutions to improve water supply. The designed low-cost household rainwater catchment system consists of an excavated cistern of 6 cubic meters volume, lined with a plastic tarpaulin sheet and covered with a wood and iron lid, and with a hand pump to extract water. The cistern should provide an average of 16 liters/day/person for the entire year for medium-size houses (roof area of 35 m2) and 21.5 liters/day/person for large-size houses (82 m2). The excavated cistern is designed with walls to stop surface runoff from entering into the cistern, and a hard cover and hand pump to extract water and minimize water contamination from faecal bacteria. The implementation of these small-scale rainwater harvesting systems should improve water quality and supply for the families of Bisate Village.

(cont.) Indeed, household rainwater catchment systems should improve water consumption from less than 5 liters/day/person to at least 16 liters/day/person. The household rainwater catchment system can provide water inside or nearby the house, which is very important as it would drastically reduce travel time for women and children to fetch water. Freeing up time from daily "water walks" could significantly improve school attendance and trade activities, leading to increased education levels and average annual income.