[athoun]

This is incorrect, or misleading at best. The map that you linked contains data about TCE levels in public water systems. It does not imply anything about the contamination of the groundwater supply which exists below many homes and workplaces in throughout the Bay Area. Contaminated soil and groundwater allows VOCs, such as TCE, to enter homes via a process called "vapor intrusion" and which can lead to negative health outcomes for the inhabitants even without ever drinking the groundwater [1].

The vast majority of the Bay Area population gets its water either from the Hetch Hetchy (SF, South Bay, Peninsula) or the Mokelumne River watershed (East Bay). This is surface water that is mostly clear of VOCs which is why nothing shows up on the map for the Bay Area that you shared.

For a more accurate representation of the state of the groundwater in the Bay Area, see this map of chemical plumes (hint they're everywhere) [2].

[1] https://www.epa.gov/vaporintrusion/what-vapor-intrusion

[2] https://web.archive.org/web/20141120123953/http://www.nbcbay...

[culi]

Fascinating. Thanks so much for taking the time to explain