Water loss investigations in the distribution system of Dar es Salaam, Tanzania

Abstract

This study was carried out to investigate water losses in the distribution system of Dar es Salaam. The water supply in Dar es Salaam has not met water demand for the past eight years. Some areas of the distribution system have been under intermittent water supply and in other areas the supply is very unrealiable, hence affecting production in industries and other important activites in hospitals, institutions and in domestic consumption. The objective of the study was to establish which areas of the distribution system have biggest water losses, what is the percentage of unaccounted-for-water or water loss in the distribution system of Dar es Salaam and what are the key factors influencing water losses in the distribution system. The water loss investigation methods used include the use of bulk flow meters to measure raw water inflow and plant outflow to check if there is more process water than minimum required. In conveyance mains water loss investigations were done by direct measurement of leaks along the trunk mains and to supplement this study a comparison was made between plant outflow rate and inflow rate at every distribution reservoir. All known consumers along the trunk mains were documented and their average consumption per connection estimated using flowmeters. The distrubution reservois were investigated by carrying out a drop test and outflow test. The distribution network was investigated by minimum night flow measurements in three pilot areas. /Kir10