WUE: Leakage and Water Loss

Training and Resources

Description: The North American Water Loss Conferences and Expositions offer attendees various approaches to reduce non-revenue water, regulatory developments, and provide a platform to share processes, methods, and techniques with peers. The conferences feature an exhibit hall with leading technology and companies providing solutions for organizations.

AWWA's Free Water Audit Software

The Water Loss Control Committee of the American Water Works Association (AWWA) created free water audit software to standardize the auditing process and provide you with a user-friendly tool to conduct a standard water audit. Once you understand where your losses are coming from through completion of a water audit, you can focus your efforts on reducing leakage to obtain real and meaningful water savings.

M36 Manual Fifth Edition 2020

AWWA’s latest edition of their M36 Manual adopted the International Water Association (IWA) water audit methodology to evaluate water loss. Completing the IWA water audit is the best action you can take to demonstrate compliance with the distribution system leakage (DSL) standard. It’s an appropriate way to show that you understand what to do to control water losses and it meets the intent of the WUE rule. This water audit method is, in our opinion, currently the best available option for you to evaluate water loss.

Terminology

Many of us have been using the term “unaccounted-for water” for years, yet the term does not have a standardized definition. All water should be accounted for, and nothing should be unaccounted for.

The WUE requirements use the terms “authorized consumption” and “distribution system leakage.” In order to account for water loss all water that enters the distribution system must go into the authorized consumption or DSL category.

Authorized Consumption

Authorized consumption is defined as the volume of water authorized for use by the water system. All unauthorized uses and any water that cannot be tracked is considered DSL.
If authorized uses are tracked and estimated these volumes of water can be added into the authorized consumption category.

You cannot estimate consumption by unmetered customers/connections to the water system. Even if these are authorized uses, they must be counted as DSL until a meter is installed.

Some examples of unmetered authorized uses that can be tracked and estimated include:

Maintenance flushing of the water system.
Cleaning water tanks or reservoirs.
Fire-fighting (hydrant).
Street cleaning.

Distribution System Leakage

Distribution System Leakage (DSL) is defined as the water lost from the distribution system and includes both apparent losses and real losses. Apparent losses include things such as theft, meter inaccuracies, and data collection errors. Real losses are the actual physical losses of water from the distribution system and include such things as reservoir overflows, leaky valves, and water main breaks. Neither apparent nor real losses are authorized uses of water, therefore they are considered leakage even if they are not actual “leaks.”

Transmission Line Leakage

Some water systems have extensive transmission lines. You may exclude transmission line losses from the DSL calculation when there is a production meter located upstream of the entry to the distribution system. If an additional production meter is not installed upstream of the distribution system, the entire transmission line losses are considered DSL.

If you are excluding transmission line leakage from DSL, you must describe transmission line leakage and the efforts taken to minimize leakage in your planning document. This does not replace any source meter requirements or waste of water requirements adopted by DOH or the Department of Ecology.

If You Can't Measure It, You Can't Manage It

To effectively manage real and apparent water loss, your water utility should be able to answer several questions.

How much did the water loss cost the utility?
Where did we lose the water?
How much water was lost, expressed as a volume and percentage?
Why did we lose the water?
Are all of our services metered (for example, city parks, and city hall)?
Have our source meters been calibrated within the last five years?
Are we using hydrant meters to track fire department or contractor uses?
Did we track the amount of water used for maintenance flushing or tank cleaning? How?
Have we sought technical assistance from leak detection experts? If not, ask an Evergreen Rural Water of Washington circuit rider to perform a leak detection survey.

Water Audit Method

Water audits are one of the most useful tools to determine your water loss. Here in Washington, ten water systems worked with national water loss control experts using AWWA methodology and best practices. They gathered and validated water loss accounting data. Read the WUE Water Audit Report (PDF) to learn more.

See our Publications and Resources page for ways to fund your leak repair projects.