Non-revenue water, or unaccounted-for water, is water that is not billed and no payment is received. Non-revenue water can cause large inefficiencies that result in a utility losing a significant amount of money over time. Utilities can conduct a water audit as part of a Water Loss Control Program to determine how much of its water is non-revenue. A water audit identifies and qualifies how water is used and how much water is lost in the distribution system. This process will allow the utility to manage its inventory properly. Once the utility can track quantities of water, it can maximize the ways that available water can be managed to meet known water needs. The function of water auditing becomes more important where available water is fully, or over-allocated.
Utilities can calculate non-revenue water using a few different approaches. Percentages are great guidelines and the most commonly used parameter. But volume of lost water in gallons is a more meaningful measurement for the general public. Volume measurements can determine revenue losses and cost effectiveness of implementing corrective action. Knowing the value of the water lost and the price of fixing the leaks, allows a utility to perform a cost-benefit analysis.
How to Measure: Volume lost (thru leaks) = (water produced or raw water pumped or water bought through the master meter) – (water sold to customers and water used for maintenance)
Let’s work a problem.
Tombstone Water Treatment Facility recently instituted a Loss Prevention Program. Tombstone produces 2.51 MGD, pumps 2.52 MGD of raw water and has a master meter reading of 2.45 MGD. Tombstone customers purchase 2.25 MGD on the average. Also, average daily water use for maintenance is 0.05 MGD. What is the amount of unaccounted-for water on a daily basis?
- Produced water: 2.51 MGD – 2.3 MGD = 0.21 MGD
- Raw water pumped: 2.52 MGD – 2.3 MGD = 0.22 MGD
- Master meter: 2.45 MGD – 2.3 MGD = 0.15 MGD