by Dr. Kelley Cullen
Providing sufficient water of appropriate quality to residents is one of the most important and challenging roles of local water districts. In a perfect world, supply would always match demand. But that is rarely the case, and water systems often end up with inefficient system leakages. A city’s distribution system leakage (DSL) is calculated as the difference between water produced or purchased and the amount of water consumption.
Because water is a valuable resource, Washington law requires that cities have a maximum three-year rolling average leakage of 10% or less. When a city is above that, they are required by law to perform a water loss control action plan.
To comply with the legislation, water districts in the State of Washington are required by the Division of Environmental Health to articulate water use efficiency goals and annual progress towards meeting those goals. Additionally, jurisdictions are required to update their goals every six years. Annual Water Use Efficiency (WUE) reports document water production, consumption and system leakage and the steps being made towards stated goals.
So, what does the data reveal about water system leakage? Not surprisingly, it is a tale of two divergent cities.
Chelan Douglas Trends 4.2.1 Total Water Produced & Share Lost to System Leakage compares data from Wenatchee and East Wenatchee, benchmarked against Walla Walla. Data is reported from 2009 through 2022 using the WUE reports.
Although Wenatchee has seen population growth of over 4,000 new residents, since 2009, the production of water has actually declined slightly from 1.45B to 1.32B gallons annually. Clearly, conservation of water has increased over the past 13 years. Unfortunately, the system leakage has more than doubled over the same period – from 9.3% to 19.7%! The current system leakage is about the same as it was in 2015, and well above the 10% state threshold.
East Wenatchee has seen both an increase in population and a corresponding increase in overall water production, however, the city has seen a decrease in water system leakage from 8.2% to only 4.7% in 2022. According to the WUE, the city has been engaging in promoting public education and awareness of conservation and is currently replacing an old water main.
So how are the cities of Wenatchee & East Wenatchee working towards improving their water use efficiency?
With nearly 20% of total water production being lost to DSL, the City of Wenatchee is working on making improvements. One of their immediate goals is to bring residential water use down to 125 gallons per capita per day by 2024. During the development of the water comprehensive plan adopted in 2019, the average daily water use for the City of Wenatchee was 135 gallons per capita per day. Based on the 2022 water use data, the current average daily water use is 133 gallons per capita per day – a slight improvement.
Specific steps being taken include showing consumption history on water bills and online. The city is also distributing leak notices and leak detection information to customers. Water use efficiency outreach and education is being provided through the Wenatchee School District afterschool program, the Cherry Creek Radio Home & Garden Expo, the Sustainable Wenatchee Earth Day Fair, and on the city’s website. The city is also engaging with residents through social media such as Facebook.
In addition to the demand side efforts, the City of Wenatchee's supply side goal was to reduce distribution leakage to 10% or less. The city has been made aware of leakages at two of the city's concrete reservoirs that are currently being monitored. One of the reservoirs is scheduled to be replaced within the next ten years. City staff have also continued to track estimated water loss during main line breaks and have implemented improved leak detection efforts.
While the City of East Wenatchee is in compliance with state water efficiency standards, they are still working to reduce their DSL. According to the latest WUE report, the city has three goals that will be revisited in 2024. First, the city would like to reduce the DSL even further, by 0.5 percentage points. Secondly, the city would like to reduce per capita water use by 2% overall. And lastly, the city is working on promoting public education and increased awareness of water conservation issues across the community.
If the WUE reports are any indication, both cities are cognizant that improving water efficiency (reducing DSL) is not a singular activity, but requires efforts aimed at reducing consumer demand as well as improving supply. And, with both cities slated to engage in new goal-setting activities in the upcoming year, it will be interesting to see subsequent improvements show up in the data.