The Safe Drinking Water Act defines public water systems as entities that provide water for human consumption to at least 15 service connections or serve at least 25 people for at least 60 days a year. Public water systems serve "the public" but may be publicly, privately, or cooperatively owned. In Washington State, public water systems are regulated by the Department of Health to ensure the water produced is safe to drink.
Roughly 75% of Thurston County residents get their water from a public water system. Total water produced by systems remained steady between 2010 to 2014 and increased slightly between 2014 and 2015.
The Department of Health identifies 7 public water system ownership types:
Special district-owned, such as Thurston PUD
Association-owned, such as a home owners association
City/town owned systems produce about 80% of total water produced, the remaining ownership categories produce less than 5% each.
Larger water systems generally have a lower and more stable leakage rates. Between 2010 and 2015 City/town-owned water systems have maintained a leakage rate of less than 10%. Leakage data is not available for systems that do not have meters for all customers.
Total Water Produced, Authorized Consumption, and Leakage
Total Water Produced − Authorized Consumption = Leakage
Total Water Produced is the amount of water pumped and dispelled from each water system’s source.
Authorized Consumption, is the total amount of water used by customers, based on data from customers' water meters.
Leakage is the difference between Authorized Consumption and Total Water Produced. Leakage is due to several causes, such as leaks in pipes and valves in the water distribution system, storage overflow, and unauthorized or unmetered consumption.