Kapiti water supply - Quantifying losses to support water management

Kapiti Coast District Council is planning to manage and meet future water demand in a potentially high growth District. The Council is currently working towards a 50-year supplementary water supply solution for the communities of Waikanae, Paraparaumu and Raumati. This project is running in parallel with Council's water conservation programme that involves a number of initiatives to reduce demand across the District. Two of the water conservation action areas are water loss reduction and data gathering.

Understanding the trends in demand and different components of demand is important for both the water conservation programme and the water supply project. To lay the foundations for this understanding, historic water consumption data was analysed from reservoir flow meters, network zone meters and commercial meters. Because the Kapiti Coast does not have universal metering, the breakdown of the total volume supplied into residential consumption and losses was not known. Using available consumption data together with a number of other data sources and tools such as BenchlossNZ, a variety of estimates were made of losses and residential use. These estimates were in reasonable agreement giving Council a realistic estimate of the true extent of losses, which were about twice what had been assumed. This work led to recommendations for improving water loss estimates and reducing water losses within the network which are now being used to inform Council's water conservation programme leading to better management of losses. This work has also contributed to Council’s recent decision to reconsider universal metering for the District.