San Jose Drinking Water Quality
What's Really in Your Tap Water?
San Jose tap water has notable issues that residents should consider. At 190.5 ppm (11.1 gpg), the water is quite hard — you may notice mineral buildup on fixtures. Lead levels test well below the EPA action level. PFAS "forever chemicals" exceed EPA limits — a water filter is strongly recommended. Only 2 minor violations in the past 3 years.
Action Needed
Quality issues detected
11.1 GPG hardness
Lead
Below EPA action level
EPA action level: 15 ppb
Hardness
Very Hard water
US Average: 100 ppm
Is San Jose Tap Water Safe to Drink?
San Jose tap water has significant quality concerns that may require action.
10 contaminants were tested in San Jose's water. 9 were detected, and 1 exceeds EPA limits.
PFAS "Forever Chemicals" — PFOS at 5.2 ppt (EPA limit: 4 ppt) — exceeds the EPA safety limit. 1 other PFAS compound was also detected within limits.
A man-made "forever chemical" formerly used in Scotchgard, firefighting foam, and industrial processes. Associated with increased cholesterol, thyroid disease, immune system suppression, and certain cancers.
→ A reverse osmosis (RO) or NSF-certified activated carbon filter can reduce PFOS by 90% or more.
Disinfection Byproducts — Trihalomethanes (TTHM) is at 76.96 ppb — 96% of the EPA limit (80 ppb). Within legal limits, but elevated.
A group of chemicals (chloroform, bromoform, and others) that form when chlorine used to disinfect water reacts with natural organic matter. Long-term exposure linked to increased risk of bladder cancer and liver, kidney, and central nervous system problems.
→ An activated carbon filter (pitcher, faucet-mount, or whole-house) effectively reduces trihalomethanes.
EPA Violations — 2 health-based violations recorded in the past 3 years across 4 water systems.
Health-based violations indicate a contaminant briefly exceeded EPA limits. The water utility is required to take corrective action.
→ Consider testing your water at home for peace of mind.
Metals — 2 contaminants detected, all within EPA limits. Highest: Chromium (VI) at 3.2 ppb (32% of EPA limit).
Inorganic Chemicals — 2 contaminants detected, all within EPA limits. Highest: Fluoride at 0.83 ppm (42% of EPA limit).
The data below shows test results from 4 water utilities serving 1.2M people in the San Jose area.
Do I Need a Water Filter?
San Jose has PFAS levels exceeding EPA limits. A reverse osmosis (RO) filter or NSF-certified activated carbon filter is recommended to reduce PFAS in your drinking water. Disinfection byproducts are elevated (above 75% of EPA limits). A carbon filter can help reduce these. With very hard water (190.5 ppm), a water softener can reduce scale buildup in pipes, appliances, and water heaters.
How Hard is San Jose Water?
190.5 ppm
11.1 grains per gallon
Very hard water causes significant mineral buildup. A water softener is recommended.
Impact on Your Home
Shower
Dries out skin & hair
Kitchen
Heavy mineral deposits
Laundry
Stiff, dingy clothes
Appliances
Significant scale
Regional Comparison
Values in ppm (mg/L as CaCO₃)
Do I Need a Water Softener?
At 190.5 ppm, San Jose has very hard water. A water softener is recommended to prevent scale buildup in water heaters, dishwashers, and pipes. Hard water can reduce appliance efficiency by up to 30% and increase energy costs. A whole-house water softener or salt-free conditioner can help.
Range: 82–545 ppm
Based on 58 samples from San Jose Water 2024 CCR (2024)
Your pipes tell a different story
The data above shows what leaves the treatment plant—not what comes out of your faucet. Old pipes, lead solder, and building plumbing can add contaminants the city never tests for. Know exactly what's in your San Jose tap water.
Home test kits detect lead, bacteria, pesticides, and 100+ other contaminants. Results in 5-10 business days from certified labs.
Lead & Contaminants
Understanding lead levels and water quality violations in San Jose
Lead Test Results
90th Percentile Lead Level
2.85 ppb
San Jose lead levels are well within safe limits.
Regular testing is still recommended, as lead can enter water through household plumbing.
Last sampled: 2025-12-31
About Lead in Drinking Water
What is Lead in Water?
Lead is a toxic metal that can dissolve into drinking water from older pipes, solder, and fixtures. It's invisible, tasteless, and odorless, making testing the only way to detect it. The EPA has set an action level of 15 ppb, though they emphasize there is no safe level of lead exposure.
Potential Health Effects
Developmental delays, learning difficulties, lower IQ, behavioral issues
High blood pressure, kidney damage, reproductive issues
How to Reduce Exposure
- •Run water for 30 seconds to 2 minutes before drinking, especially in the morning
- •Use cold water for cooking and drinking (hot water dissolves more lead)
- •Install a NSF-certified filter designed to remove lead
- •Test your water, especially if your home was built before 1986
PFAS “Forever Chemicals”
1 PFAS chemical exceeds EPA limits
PFAS are synthetic chemicals that don't break down in the environment. A reverse osmosis or activated carbon filter can reduce PFAS levels.
Total Trihalomethanes (TTHM)
96% of EPA limit
Range: 3.12–76.96 ppb
Haloacetic Acids (HAA5)
60% of EPA limit
Range: 0–35.8 ppb
Fluoride
42% of EPA limit
Range: 0.6–0.93 ppm
Chromium (VI)
32% of EPA limit
Range: 0–8.2 ppb
Other Detected Contaminants
10 contaminants detected
| Contaminant | Your Water | Limit (MCL) | Status |
|---|---|---|---|
Chromium (VI) | 3.2 ppb Range: 0-8.2 Groundwater | 10 ppb Goal: 0.02 ppb | Safe 32% of limit |
Fluoride | 0.83 ppm Range: 0.6-0.93 VW Imported Surface Water (treated) | 2 ppm Goal: 1 ppm | Safe 42% of limit |
Nitrate (as N) | 3 ppm Range: 0-6.5 Groundwater | 10 ppm Goal: 10 ppm | Safe 30% of limit |
Barium | 0.18 ppm Range: 0-0.3 Groundwater | 1 ppm Goal: 2 ppm | Safe 18% of limit |
Total Trihalomethanes (TTHM) | 76.96 ppb Range: 3.12-76.96 Highest site average - very close to MCL | 80 ppb | Caution 96% of limit |
Haloacetic Acids (HAA5) | 35.8 ppb Range: 0-35.8 Highest site average | 60 ppb | Caution 60% of limit |
Chlorine | 1.17 ppm | 4 ppm | Safe 29% of limit |
PFHxS | 3.72 ppt Range: 0-5.5 UCMR5 - 12/36 samples detected | 10 ppt Goal: 10 ppt | Safe 37% of limit |
PFOA | 0 ppt Range: 0-0 ND - UCMR5 - 0/37 samples detected | 4 ppt 0 | Safe |
PFOS | 5.2 ppt Range: 0-6.2 UCMR5 - 2/37 samples detected - Max 6.2 ppt exceeds EPA MCL of 4 ppt | 4 ppt 0 | Exceeds 130% of limit |
MCL = Maximum Contaminant Level (EPA legal limit)
EPA Compliance History
Action Recommended
Active health-based violations detectedConsider using a certified water filter until violations are resolved. Contact your utility for updates on corrective actions.
3-Year Violation Summary
2
Total Violations
2
Health-Related
0
Administrative
Health-Related Violations
Contaminant exceeded EPA safety limits. May require filter or alternative water source.
Administrative Violations
Missed testing deadlines or reporting. Does not indicate water quality issues.
Who Provides San Jose's Water?
Utility Name
SAN JOSE WATER
EPA System ID (PWSID)
CA4310011
Primary Water Source
Surface Water
Population Served
1.2M
Frequently Asked Questions
Common questions about San Jose tap water quality
Nearby Cities in California
Los Angeles
Hard water
East Bay
Very Hard water
San Diego
Very Hard water
California
Hard water
Eastern Municipal Wd
Very Hard water
Fresno
Moderate water
This data is for informational purposes only. Water quality can vary by neighborhood and building. For official reports, contact your local water utility or the EPA. Learn about our methodology
Data source: San Jose Water 2024 CCR (2024) • View report