Water in California.
California has the most comprehensive state-level water monitoring in the U.S. and the strictest contaminant-specific public-health goals. Hexavalent chromium (the Erin Brockovich contaminant) is widely monitored after Hinkley. Central Valley agricultural runoff drives nitrate exposure in farm-belt communities.
California's OEHHA public-health goals are the reference for most EWG health-protective guidelines nationwide.
How California regulates drinking water.
Strictest state in the country. OEHHA Public Health Goals are stricter than federal MCLs for nearly every contaminant. State has its own MCL for chromium-6 (10 ppb), perchlorate, and PFAS Response Levels. AB 685 recognizes the Human Right to Water.
State Water Resources Control Board — Division of Drinking Water
California's water history, in order.
The contamination events, regulatory shifts, and major settlements that define how this state thinks about drinking water today.
- 1993
Hinkley chromium-6 contamination becomes a national story (later the basis for Erin Brockovich).
- 2012
AB 685 makes safe drinking water a state-recognized human right.
- 2014
California sets the first state-level chromium-6 MCL in U.S. history (10 ppb).
- 2019
SAFER Drinking Water Program launched, targeting ~1M residents on failing systems.
- 2023
State adopts response levels for PFAS PFOA (10 ng/L) and PFOS (40 ng/L) ahead of federal rule.
The actual water you drink.
The physical rivers, aquifers, lakes, and reservoirs that feed California's public water systems. Source quality is the foundation of tap quality — and where the long-term protection fights happen.
- riverSacramento-San Joaquin Delta
State Water Project + Central Valley Project hub serving 25M+ Californians.
- reservoirHetch Hetchy Reservoir
SF Bay Area pristine Sierra snowmelt.
- riverColorado River
Southern CA via Metropolitan Water District.
- riverOwens Valley Aqueduct
LADWP system since 1913.
- aquiferCentral Valley Aquifer
Heavily depleted from decades of agricultural pumping.
Source-water mix
~55% surface water, ~45% groundwater (varies by region)
Major cities served
Los Angeles · San Diego · San Francisco · San Jose · Sacramento · Fresno
Who actually serves the water.
The largest public water systems in California by population served. Click your ZIP after to see the full live EWG report for your specific utility.
- Los Angeles Department of Water and PowerLos Angeles4,000Kserved
- Metropolitan Water District of Southern CaliforniaMulti-county· Wholesale provider serving 26 member agencies.Wholesale provider serving 26 member agencies.19,000Kserved
- San Francisco Public Utilities CommissionSan Francisco / Hetch Hetchy2,700Kserved
- San Diego County Water AuthoritySan Diego3,300Kserved
- Santa Clara Valley Water DistrictSan Jose metro2,000Kserved
Where the contamination comes from.
Every state has a different industrial fingerprint. The industries below are the dominant historical and active contamination sources in California's drinking water systems.
Central Valley agriculture (nitrate, atrazine) is the dominant rural exposure source. Silicon Valley legacy semiconductor solvents drive multiple Superfund sites. Aerospace and military bases (especially Camp Pendleton, Edwards AFB, Travis AFB) are major PFAS sources.
What state data flags most consistently.
Drawn from EPA SDWIS sampling records, EWG state summaries, and regional regulatory action over the past five years. Read the full deep dive on each.
Chromium-6 (Hexavalent Chromium)
The Erin Brockovich chemical. A known carcinogen with no federal-specific limit yet.
Arsenic
A naturally occurring carcinogen. Highest in private wells and the rural Southwest.
PFAS (Forever Chemicals)
A class of ~15,000 synthetic chemicals that don't break down. Now regulated for the first time.
Nitrate
Fertilizer and animal waste runoff. Acutely dangerous for infants under 6 months.
Trihalomethanes (TTHMs)
Byproducts of chlorinating water. Linked to bladder cancer at chronic exposure.
Risk isn't evenly distributed.
Roughly 1 million Californians — disproportionately Latino, low-income, and rural — are served by community systems that fail SDWA standards. The SAFER program targets this gap.
~5% of California households on private wells. Central Valley well users face the most-documented contamination.
What's coming for California's water.
Multi-year megadrought reshapes Sierra snowpack and Colorado River allocations. Wildfire-burn-scar runoff contaminates surface intakes (Camp Fire / Paradise documented). Sea-level rise threatens Delta levees and Bay Area shallow aquifers.
Statewide mandate
AB 746 (2017) requires every K-12 school in California to test drinking water for lead. Schools with results above 5 ppb must take corrective action. Results are publicly available.
Five questions for your next Consumer Confidence Report.
Your utility is required to send you a Consumer Confidence Report annually. Most are dense and procedural. These are the questions worth following up on for California specifically.
- 1
Is my system on California's SAFER Drinking Water Program failing-systems list?
- 2
What is my utility's chromium-6 (Cr-6) average? California's MCL is 10 ppb.
- 3
Are my school's most recent lead test results published on the SWRCB site?
- 4
Does my utility have an Urban Water Management Plan accounting for State Water Project cutbacks?
- 5
Are there any Public Health Goals (PHGs) my utility is exceeding even if it's not violating the federal MCL?
Most state regulators allow public records requests for the underlying lab reports behind your CCR — your utility should be able to provide them on request.
What's changed in California water law.
Drinking water regulation moves at the state level as much as the federal level. Below are notable recent bills and regulatory actions specific to California.
- 2024
SB 1115 — Updated state PFAS response framework aligning with federal rule.
- 2023
AB 685 implementation — Human Right to Water progress reporting requirements expanded.
- 2022
SB 222 — Lead Service Line Replacement bond program established.
Reverse osmosis is the most universally effective home solution for California's diverse contaminant profile. For chromium-6 specifically, NSF/ANSI 58 RO is the recommended path.
We don't recommend brands — the NSF/ANSI certification number matters more than the name on the box.
This is the state. Your address is the answer.
State-level patterns don't tell you about your specific tap. Run your ZIP for the live EWG contaminant report on your utility — or build a personalized Water File for your household.
Source-water mix, utility counts, lead-service-line estimates, and private-well shares are approximate, drawn from EPA SDWIS public data and state primacy-agency summaries. Contaminant rankings reflect EWG state-level monitoring data and regional regulatory action — they are not exhaustive. Timeline events are publicly documented. See methodology for the full sourcing. Search EPA SDWIS for California