Water Quality

The City's drinking water supply meets or exceeds state and federal drinking water standards. Water sampling is performed weekly and submitted to an independent lab for analysis. The results are reported to the State Water Resources Control Board.

The Division of Drinking Water (DDW) has implemented a new procedure to access water quality monitoring notification documents. To access, go to the Drinking Water Watch website (https://sdwis.waterboards.ca.gov/PDWW/) and enter the Water System Number or the Water System Name for which you would like to search. 

Is Patterson tap water safe to drink?

Yes. Patterson water is routinely tested for more than 100 potential contaminants, including both regulated and unregulated substances. Our extensive testing confirms that we meet or exceed all federal and state drinking water standards.

Where does my drinking water come from?

The city relies solely on groundwater—drawn from the Delta-Mendota Subbasin for its water supply. Ground water is water located below the ground where it collects in pores and spaces within rocks and in underground aquifers. We get water by drilling wells and pumping it to the surface. The water then travels to your tap through the city’s water distribution system. 

How is my drinking water regulated?

All public water systems in the United States are required to follow the standards and regulations set by the U. S. Environmental Protection Agency (EPA) and the State Water Resources Control Board (SWCRB), Division of Drinking Water (DDW). Regulations for these agencies protect public water systems but do not apply to privately owned wells or other individual water systems. 

How often does the local public water system test my drinking water?

Frequency of drinking water testing depends on the number of people served, the type of water source, and types of contaminants. The city of Patterson has 25 sampling stations throughout the city and tests weekly. Other contaminants are tested on a quarterly or yearly basis, as established by DDW and the EPA. You can find out about levels of regulated contaminants in your water for the previous calendar year in your annual Consumer Confidence Report (CCR).

How can I find out if there has been a violation in our public water standard?

When water quality standards have not been met, your public water system must alert and notify customers if there is a risk to their health. Your annual Consumer Confidence Report (CCR) is another way to find out about the water quality in your area, and find information regarding contaminants, possible health effects, and the city’s water’s source. There are currently no violations for the city of Patterson.

How do germs and chemicals get into my drinking water?

There can be many sources of contamination of our water systems. The most common sources of contaminants include:

  • Naturally occurring chemicals and minerals (e.g., arsenic, radon, uranium, hexavalent chromium)
  • Local land use practices (e.g., fertilizers, pesticides, livestock, concentrated animal feeding operations)
  • Manufacturing processes
  • Sewer overflows
  • Malfunctioning wastewater treatment systems (e.g., nearby septic systems)

The EPA and SWRCB regulate many contaminants that pose known human health risks. They make sure that water meets certain standards, so you can be sure that high levels of contaminants are not in your water.

Who should I contact if my water has a funny smell, taste, or appearance?

A change in your water’s taste, color, or smell is not necessarily a health concern. However, sometimes a change can be a sign of problems. If you notice a change in your water, call Public Works immediately at (209) 895-8060.