Your water is regularly tested for more than 120 chemicals and other substances, as well as radioactivity. The table below provides detailed information about the water that comes from your tap after it is treated (treated water) and before it is treated (raw water). The substances shown are ones that our customers have the most questions about.

You can also view the latest Annual Water Quality Report, which lists the annual results for these substances as well as many others.

For a comprehensive list of contaminants that we test for and have not been detected in our water supply, see our 2019 Contaminants Not Detected List (PDF).

Also, the United States Environmental Protection Agency has additional contaminant list information about the fourth Unregulated Contaminant Monitoring Rule (UCMR 4). For general background information, see their UCMR Basic Information Fact Sheet (PDF).