Investigating unaccounted for water and its components in Zomba City water supply system, Malawi

Abstract

This study assessed Unaccounted for Water (UFW) in Zomba City, Malawi in 2009 and quantified its real and apparent loss components. The study was carried out in the period January–May 2009 and focussed on three selected water supply zones (Airwing, Malonje and Sadzi) especially for determination of the components of non-revenue water (NRW). Field measurements of flow and utility records formed the basis of the study. It was established that the NRW for Zomba for the period 1999–2008 ranged from 20 to 36%. During the study period, the average UFW in the specific study areas was 13% of which 81% were real losses (Airwing); 62% with 58% real losses (Malonje); and 51% with 60% real losses (Sadzi). It was concluded that UFW for 2009 Zomba was above 23%, achieved by good performing water utilities in developing countries. Real losses were higher than apparent losses in all three specific study areas and this was driven by pressure. The study recommends real loss reduction through pipe replacement and improved pressure management, and apparent loss reduction through improved metering. Reduction of water losses is imperative in the wake of climate change and the need to attain Sustainable Development Goals.