For utility managers to best select technology interventions to address water losses in their systems, it is important to understand the standard vocabulary terms used industry-wide. Some of those terms include non-revenue water (NRW), real water loss, and apparent water loss.
The American Water Works Association (AWWA) categorizes the water balance as either authorized consumption or water losses. Overall water losses are considered non-revenue water. This is water that is not formally billed and for which no payment is received. Authorized consumption refers to water which can either be billed or unbilled, metered, or unmetered. Examples of unbilled authorized consumption are fire flows or water main flushing events.
Water losses are categorized as apparent or real. Apparent (sometimes called commercial) losses occur when water that should be included as revenue generating water appears as a loss due to unauthorized actions or calculation errors. Apparent losses consist of erroneous meter readings, data handling errors, or in circumstances of unauthorized consumption, such as theft. Real losses are actual physical water leaks from a storage system and consist of leakage from tanks, transmission and distribution mains, and service lines up to and including the meter. Leaks on the customer side of the meter are not included in this category. Real losses can also be separated into surfacing and non-surfacing leaks.
Apparent losses are managed through checking, calibrating, and replacing inefficient meters. Data management tools can also be used to ensure all meters are read consistently and accurately. System inspections for water theft are also important tools for managers to use to reduce apparent losses.
Real Losses are managed through pro-active leak detection programs including acoustic leak detection and soil moisture sensing to search for non-surfacing leaks. Surfacing leaks are typically reported by customers or concerned citizens and utility operators log them into a work order system so they can be routinely inspected and repaired. Non-surfacing leaks are the most critical ones to identify and repair to reduce real water loss effectively and permanently. The reduction of real water losses saves water at the same time as it reduces energy consumption and reduces greenhouse gas emissions. Reducing water loss allows the utility to be more fiscally responsible, minimizing operating costs and customer prices.
ASTERRA is the leader in identifying real water losses in potable water systems, specializing in finding non-surfacing leaks in an efficient and cost-effective manner using Synthetic Aperture Radar (SAR) for satellite-based leak detection, infrastructure analysis, and infrastructure maintenance services.