Redmond supplies drinking water to customers from five City supply wells and from Seattle Public Utilities (SPU) Tolt River Watershed. The City supply wells pump groundwater, which is water stored underground in the pores between the sand and gravel that are under Redmond. Although PFAS are not regulated contaminants, and routine testing is not required, the cities of Redmond and Seattle tested their water sources in 2015 and found no detection of PFAS. The City of Seattle conducted additional testing in 2018 and again found no detection of PFAS in the Tolt River Watershed supplies. Redmond conducted additional testing in 2020 and found trace amounts of PFAS in one water supply well. This well has been taken out of production and no longer supplies drinking water to residents. The City will re-sample all the drinking wells in November 2023 for PFAS following the latest sampling protocols.