California Water Quality Report
Tap water quality data for 83 cities in California, updated 2026.
US average: 100 ppm
78 of 83 cities violation-free
82 cities tested
83 water systems tracked
Cleanest Tap Water in California
Cities with the fewest water quality issues
Los Angeles
3.9M served
East Bay
1.4M served
San Diego
1.4M served
California
1.0M served
Eastern Municipal Wd
667K served
Fresno
546K served
Sacramento
520K served
Long Beach
467K served
Irvine Ranch
445K served
Anaheim
349K served
Most Water Quality Issues in California
Cities with the most violations and concerns
Water Hardness Across California
Not sure what your hardness means? Use our Water Hardness Calculator or find the best hardness test kits.
California Tap Water: What You Need to Know
California has 83 tracked water utilities serving approximately 23.9M residents. The average water hardness is 236 ppm (13.8 GPG), classified as Very Hard — above the national average of 100 ppm. Hardness ranges from 4.8 ppm in Cws - Visalia to 749 ppm in Vallecitos Wd.
In the past 3 years, 5 of 83 cities in California have recorded water quality violations, totaling 145 violations (16 health-based). All 82 tested cities have lead levels below the EPA action level of 15 ppb.
With very hard water on average, many California residents may notice mineral buildup on fixtures, dry skin, or stiff-feeling hair. A shower filter for hard water can help reduce chlorine exposure, while a water softener addresses the mineral buildup directly.
Frequently Asked Questions About California Water
Is tap water safe to drink in California?
Most tap water in California meets EPA standards, but 5 cities have recorded violations in the past 3 years (16 health-based). We recommend checking your specific city's report on TapWater.org and considering a home water test.
How hard is the water in California?
California's average water hardness is 236 ppm (13.8 GPG), classified as Very Hard. This is above the national average of 100 ppm. Hardness varies significantly by city — use our Water Hardness Calculator to check your specific area.
Which city in California has the cleanest tap water?
Based on EPA violation data, lead testing, and water quality metrics, Los Angeles ranks as having the cleanest tap water in California. It has zero violations in the past 3 years and lead levels well below the EPA action level.
Which city in California has the most water quality issues?
Sunnyvale currently has the most water quality concerns in California, with 126 violations in the past 3 years. Residents should check their city's detailed water quality report and consider using a certified water filter.
Where does California get its water from?
The majority of California's water systems (80%) use surface water as their primary source. Surface water comes from rivers, lakes, and reservoirs. Each city's specific source can vary — check individual city reports for details.
48 of 83 Cities
Sorted by population served
Los Angeles
Utility serves 3.9M
East Bay
Utility serves 1.4M
San Diego
Utility serves 1.4M
San Jose
Utility serves 1.2M
California
Utility serves 1.0M
Eastern Municipal Wd
Utility serves 667K
Fresno
Utility serves 546K
Sacramento
Utility serves 520K
Long Beach
Utility serves 467K
Irvine Ranch
Utility serves 445K
Anaheim
Utility serves 349K
Santa Ana
Utility serves 311K
Riverside
Utility serves 298K
Santa Clarita Valley
Utility serves 294K
Gswc - Southwest
Utility serves 278K
Helix
Utility serves 278K
Coachella Vwd: Cove Community
Utility serves 270K
Cws - Bakersfield
Utility serves 268K
San Gabriel Valley
Utility serves 258K
Modesto
Utility serves 246K
Otay
Utility serves 238K
San Gabriel Valley Wc - Fontana
Utility serves 238K
Golden State
Utility serves 225K
San Bernardin0
Utility serves 215K
Cucamonga Valley
Utility serves 211K
Los Angeles Cwwd 40 Reg 4 & 34 Lancaster
Utility serves 208K
Huntington Beach
Utility serves 201K
Oxnard
Utility serves 200K
Contra Costa
Utility serves 198K
Stockton
Utility serves 197K
Sweetwater Authority
Utility serves 191K
Liberty
Utility serves 190K
Glendale
Utility serves 189K
Marin Municipal
Utility serves 187K
Ontario
Utility serves 185K
Scwa - Laguna/vineyard
Utility serves 185K
Santa Rosa
Utility serves 175K
Garden Grove
Utility serves 174K
Oceanside
Utility serves 171K
Moulton Niguel
Utility serves 170K
Elsinore Valley Mwd
Utility serves 169K
Corona
Utility serves 169K
Santa Margarita
Utility serves 168K
Pasadena
Utility serves 164K
Hayward
Utility serves 163K
Bakersfield
Utility serves 160K
Sunnyvale
Utility serves 158K
Roseville
Utility serves 156K