Two Different Approaches to Quantifying Revenue Loss Are Used to Highlight the Effects of Meter Inaccuracy at Low Flow Rates and Their Consequences for a Utility’s Bottom Line

R eduction of nonrevenue water use is currently a common goal for most water distribution systems. Nonrevenue water consists of water lost either through real losses (e.g., underground leakage) or through apparent losses (e.g., metering inaccuracies and unauthorized use). Reducing the apparent losses caused by meter inaccuracies at low flows can result in substantial short-term increases in utility revenue and lead to increasingly equitable service charges for water users in the long term. This article describes two methods for estimating apparent losses caused by meter inaccuracies that should help municipal utilities better understand the consequences of meter accuracy at low flow rates. The authors also provide the average low-flow accuracies of several meter types, should current system information be incomplete or unavailable. These accuracy data were obtained as part of the Water Research Foundation project Accuracy of In-Service Water Meters at Low and High Flow Rates, which is investigating the accuracies of water meters at flow rates below the AWWA minimum flow rate standard. These data facilitate comparison of current in-service meters with different meter types. In light of the prospect of increased utility revenue and ability to account for water supplies, lowflow accuracy of residential water meters represents a key consideration for utilities in selecting a water meter.