Cost-effective management of leakage has driven the sectorization of water supply networks into discrete areas that are referred to as District Metered Areas (DMAs). The resulting change in network topology has a major impact on the hydrodynamic conditions and consequently changes in water quality. This paper investigates the impact of DMAs on the potential for discoloration by analysing the spatio-temporal distribution of historic discoloration-related customer contacts for a UK water company. The results demonstrate that the sectorization of networks could have a negative effect on discolouration. A management strategy to reduce the risk of discoloration in DMA-based systems is discussed.