This feature set provides locations where water testing exceed the Public Health Goals (PHGs) established by the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA). The water tests were collected by the San Francisco Estuary Partnership alongside community-based partners and Tribes from around the San Francisco Bay Region. While the tap water testing project was conducted to provide useful insight into water quality in the region, participants were self-selected. The effort was designed to test the water of those who expressed concern and had a desire to learn more to understand potential issues and their solutions and this effort should not be construed to be a rigorous scientific study.

A PHG is the level of a chemical contaminant in drinking water that does not pose a significant risk to health. PHGs are not regulatory standards. However, state law requires State Water Resource Control Boards (SWRCBs) to set drinking water standards for chemical contaminants as close to the corresponding PHG as is economically and technologically feasible. In some cases, it may not be feasible for SWRCB to set the drinking water standard for a contaminant at the same level as the PHG. The technology to treat the chemicals may not be available, or the cost of treatment may be very high. SWRCB must consider these factors when developing a drinking water standard.

The process for establishing a PHG for a chemical contaminant in drinking water is very rigorous. OEHHA scientists first compile all relevant scientific information available, which includes studies of the chemical's effects on laboratory animals and studies of humans who have been exposed to the chemical. The scientists use data from these studies to perform a health risk assessment, in which they determine the levels of the contaminant in drinking water that could be associated with various adverse health effects. When calculating a PHG, OEHHA uses all the information it has compiled to identify the level of the chemical in drinking water that would not cause significant adverse health effects in people who drink that water every day for 70 years. OEHHA must also consider any evidence of immediate and severe health effects when setting the PHG.

This data set was collected through a California Department of Water Resources grant that worked with disadvantaged and underserved communities and Tribes to collect data on tap water quality throughout the region in response to distrust in tap water documented during the San Francisco Bay Regional Water Needs Assessment. This tap water testing effort was envisioned and implemented by the community and Tribal partners that the San Francisco Estuary Partnership worked with during the Regional Water Needs Assessment Process and was supported technically and programmatically by the San Francisco Estuary Partnership, UCLA Luskin Center, Woodard and Curran, and Lotus Water. All of the locations have been slightly modified (between 0.5 and 2.5 blocks) to protect the personal information of the project participants.