Every day, between 10 and 30 percent of water pumped is lost or unaccounted for. Known as non-revenue water (NRW), this lost water costs utilities a lot – not only in water, but in energy.
A water utility’s energy expenditure can exceed 65 percent of its annual budget, according to Frost & Sullivan. The World Bank estimates that NRW costs utilities $14 billion annually worldwide.

The need to prevent non-revenue water losses and protect precious water resources has become increasingly important. An advanced metering infrastructure (AMI) system can be a fundamental component of any non-revenue water (NRW) detection program. Detecting and stopping distribution leaks allows water that would have otherwise been lost to be billed.

While many solutions exist to address NRW, no single product alone can solve the problem of NRW. It requires a comprehensive approach that addresses the issue from various angles, which could include acoustic leak detection, district metering, pressure management and tamper alerts. Each method leverages specific aspects of AMI technology to find leaks in different ways.

First, acoustic leak detection is an important way that utilities can identify and account for non-revenue water. A dynamic combination of acoustic leak sensors, AMI technology, and innovative data analysis software enables proactive leak mitigation. Using a communication module with an integrated acoustic leak sensor, water providers can collect and analyze vibration patterns from anywhere in the distribution system—significantly improving their ability to proactively maintain critical water infrastructure.

Proactive acoustic leak detection programs can also improve customer service. The acoustic sensors can detect customer-side leaks, allowing the utility to notify customers of potential leaks before they experience a high water bill or sustain damage to their property.

The second way in which utilities can identify NRW is by performing district metering analysis. By grouping and aggregating data stored in an analytic software application, district metering can be performed. This process consists of a few simple steps:

  1. Identify the meter or meters that feed water into the district (i.e. the “master meter”).
  2. Identify the group of meters in the district and aggregate the total consumption of these meters on an interval-by-interval basis. Accrue the aggregated consumption of the district into a virtual meter.
  3. Compare the net consumption of the master meter (the measured input to the district) with the metered consumption of the aggregated district (the measured consumption within the district) on a time-synchronized interval-by-interval basis. Any difference between the net consumption of the master meter and the aggregated consumption of the virtual meter is considered non-revenue water, which can include leaks.

NRW can result from a variety of factors, including leaks, theft, inaccurate metering and non-metered services such as fire hydrants. However, once the district metering analysis has been conducted and the analytics application has ranked the various districts according to severity, much more is known about where to look for leaks throughout the network than was known before the analysis was conducted – all accomplished without ever having to leave the office.
Pressure management is another effective way to control the amount of water lost in a system. A small reduction in pressure can mean a significant reduction in real losses through leaks. When activated during low demand periods such as late at night or early in the morning, pressure management won’t affect service levels and can reduce consumption in networks with no intermediate storage.

With a pressure management program, a utility’s distribution system is broken down into pressure zones. Pressure is monitored at the inlet, average zone point and the critical zone point. The average zone point is a location that exhibits the average pressure rate for the zone. The critical zone point is a location where pressure is the lowest, usually the highest elevation in the zone.

The reduction of pressure greatly reduces the amount of night flow when the system is quiet.

Lastly, utilities can leverage tampers to combat NRW. With some AMI systems, a tamper flag is sent whenever the connection between the meter and meter interface unit (MIU) is opened. More specifically, a communication module takes a consumption reading each hour, at the top of the hour, and places this reading into its memory. When this reading is taken, the module can detect if there is no connectivity to the meter register, and if this occurs, the communication module marks this account as having a potential tamper and includes a “tamper flag” with its next data transmission.

Through acoustic leak detection, district metering, pressure management, and tamper analysis, utilities can reduce NRW and thereby reduce the amount of water they have to pump and treat to meet current and future demand. This reduces the amount of energy required to pump the water, the amount of water lost and the amount of CO2 produced. In the end, it enables utilities to recover lost revenues and protect precious water resources, creating a sustainable future for their customers and their businesses.

This week our team will be at the American Water Works Association Conference in Boston. We hope you’ll visit us in booth #1806 to learn more about these solutions.

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Joe Ball
Water Sales - Itron