Approximately 370,000 Californians’ drinking water is highly contaminated with chemicals that harm human health, according to an analysis led by researchers at the University of California—Berkeley and the University of California—Los Angeles.
The study, published Dec. 22, 2021, focused on the three pervasive chemical contaminants: arsenic, nitrate, and hexavalent chromium. Arsenic naturally exists in groundwater, whereas nitrate and hexavalent chromium are often produced in agricultural and industrial activities.
Lara Cushing, an assistant professor of environmental health sciences and presidential chair of UCLA Fielding School of Public Health, said the number of residents impacted by unsafe drinking water is likely to be underestimated.
“Because this study is limited to three common contaminants, the results likely underestimate the actual number of Californians impacted by unsafe drinking water from other chemicals,” Cushing said in a statement.
She also said that the most concentrated area affected by the contaminated water is a poor and rural area in the San Joaquin Valley, about 40 miles east of San Francisco, where people rely heavily on privately-owned wells.
Although the community water systems have been commonly monitored for contaminant levels under federal regulation, many of them do not meet the regulatory standards. Despite the federal regulation, many private-owned domestic wells remain unregulated.
The analysis also reveals that over 1 million people in California rely on domestic wells for their water supply.
More than one-third of people whose water supply is found to likely contain chemical contaminants are currently relying on domestic wells, according to the study.
“I think a lot of people might be surprised to learn that, given how wealthy the state of California is, we still don’t have universal access to clean drinking water,” Cushing said.
The team also released an online Drinking Water Tool for Californians to look up where their water comes from and a water contamination map.
Drinking water with an unsafe level of contaminants can cause gastrointestinal illnesses, reproductive effects, and chronic diseases such as cancer. Long-period time of chemical exposure may lead to severe organ damage, skin discoloration, and developmental effects, according to the United States Environmental Protection Agency.