Losses in drinking water systems are inevitable. Natural evaporation, friction losses and pipeline leakage will occur.

The question is how to limit those losses (nonrevenue water) and maximize the share of treated water billed to customers.

Of primary concern are losses to aging or deteriorating pipeline infrastructure, pressure management issues, fire hydrant flushing and even improperly metered consumption. All these will plague a water utility or community’s bottom line.

These real and apparent water losses must be managed through strategies such as leak detection and repair, regular distribution system monitoring and accurate flow measurement throughout the pipeline network.

Without reliable, accurate flow measurement instrumentation delivering real-time, consistent data, water professionals will struggle to identify sources of water loss, adequately bill for consumption and diagnose pipeline problems before they become full crises.

Common approaches

Nonrevenue water poses a growing challenge, and there is no silver bullet for tackling it. Most water agencies use a variety of techniques to improve pipeline inefficiency, enhance decision-making and prevent financial losses. Some popular practices include:

• Pipeline inspection technologies. Tools like acoustic sensors and pressure loggers are easy to use and can detect leaks and air or gas pockets in pressurized pipelines. Many such devices are IoT-friendly and can be interconnected with other technologies like GIS to give users a more holistic understanding of network health.
• Pressure management. Some utilities segment water distribution into smaller networks called district metered areas or zones to simplify network monitoring easier. Pressure-regulating valves or advanced pressure management systems can help reduce stress on the pipeline. However, sudden changes in transient flow, such as pump startups or shutdowns, fire hydrant use and valve closures, can cause older or weaker pipelines to break or leak despite pressure management practices.
• Water loss audits and system upgrades. This is the best way to minimize nonrevenue water, but a study by the Utah Water Research Laboratory found that only 43.5% of utilities regularly assess their mains. Meanwhile, nearly 20% of mains in the U.S. and Canada are past their life expectancy. In addition, budget and staff constraints keep many utilities from conducting regular audits and upgrades.
• Metering upgrades. A good way to monitor water usage, and compare data against readings from distribution flowmeters, is to equip each residence and commercial building with a water meter compatible with advanced metering infrastructure. Metering on fire hydrants can account for water loss during routine flushes.

Flowmeter options

One technique to combat leakage and proactively diagnose pipeline issues is to install high-quality, precision flow measurement instrumentation throughout the distribution network in locations such as trunk mains, district metered areas or distribution mains.

Smart meters that provide real-time, accurate flow data can help users establish a baseline for pipeline performance and consumer water usage. This helps identify discrepancies in data that may indicate pipeline problems related to nonrevenue water.

Regular analysis of flow data at various metering points throughout the network, including raw water intake, treatment plant, distribution and end points, can enhance billing accuracy, identify potential losses and allow utilities to quantify water efficiency and potential return on investment. Users can select from numerous measurement technologies to suit their unique locations and installation conditions. Some common flowmeter types are:

• Propeller meters. These meters are cost-effective for utilities that require broad deployment in low-accountability areas or where users need baseline flow estimates to pinpoint nonrevenue water. The meters are durable and easy to install for temporary applications, such as hydrant flushing.
• Ultrasonic meters. Commonly operating on transit-time or Doppler principles, these meters for closed pipelines are portable, highly accurate and noninvasive. Clamp-on meters are easy to install and keep pipelines running, but installation for applications such as buried pipelines can be a challenge. In the right settings, these meters can be beneficial for nonrevenue water monitoring for short-term diagnostic projects.
• Electromagnetic meters (mag meters). Offered in full bore and insertion styles, these devices can accommodate a variety of line sizes while providing precise readings. They are robust devices for applications that require the utmost accuracy and minimal maintenance. Insertion style units can suit tough installations where traditional full-bore units cannot. These include small spaces or where construction may pose a problem.

Features to consider

A meter is only as good as the data it provides. When seeking the right meter for a nonrevenue water application, remember the features and meter functionality required to best benefit your flow project:

• Installation capability. Consider the application location. Is it hard to access? Will it require heavy construction? Will a complete shutdown of the area and pipeline be too big an inconvenience? Also consider the maintenance requirements as they relate to the installation location.
• Communication outputs. What are the data frequency and transmission requirements? Meters used for billing may require AMI or automated meter reading capability, while meters transmitting flow data to treatment plants may require pulse or 4-20 mA output. Consider products that help you plan for the future, such meters whose communication protocol can be changed in the field instead of being sent back to the factory for recalibration.
• Accuracy and repeatability. Accuracy is important, but repeatability is critical. Repeatability is the likelihood that under the same flow conditions the meter will produce the same accuracy again and again. If a flowmeter gives consistent readings, it is easier to trust it and to adjust for small errors.
• Data integration: A meter with a datalogger may be beneficial for projects that experience unreliable power or are in remote locations. Dataloggers ensure that users have reliable records and reports needed for tracking trends and spotting nonrevenue water early. Make sure flow data can integrate with your management system software.

Getting started

Investing in any method of nonrevenue water detection and remediation can be overwhelming, especially for a utility with a tight budget and a sprawling conveyance system. When undertaking a metering project for leak detection or other nonrevenue water purposes, start small.

If unfamiliar with metering in general, or if new to a technology or manufacturer, invest in only a few meters at first. Observe the meters’ installation, startup and operation and become familiar with the product and the flow data provided before expanding the project.

And finally, collaborating with experts in flow measurement on a nonrevenue water project will ensure that you have a partner in your success. Flow service providers, engineering consultants or manufacturers’ representatives can assist with installation and startup as well as any necessary maintenance.