Water Quality

The City relies solely on groundwater—drawn from the Delta-Mendota Subbasin (in the San Joaquin Valley Basin)—for its water supply. Groundwater beneath the city of Patterson is present in two aquifers, a lower confined zone and an upper unconfined zone. The two aquifers are separated by the thick, semi‐impermeable Corcoran Clay layer. Potable water is drawn from the lower aquifer, which contains water generally suitable for potable use and requires only disinfection prior to distribution. Water found above the clay layer is extracted for non-potable use, with constituent levels above those acceptable for potable consumption. This water is used for irrigation at parks and large landscaped areas. Our water supply is regulated by the California State Water Resources Control Board (SWRCB). Currently, the city's drinking water supply meets or exceeds all state and federal drinking water standards. Water sampling is performed weekly and submitted to an independent lab for analysis. Every year a report is distributed that lists all constituents sampled, sampling dates and any levels detected. These reports can be viewed below:

2017 Consumer Confidence Report (PDF)

2016 Consumer Confidence Report (PDF)

2015 Consumer Confidence Report (PDF)

2014 Consumer Confidence Report (PDF)

If you have any questions or concerns on the city's water supply, please call Public Works at (209) 895-8060 or email Public Works.