Nitrate in San Francisco, CA Drinking Water
Nitrate data for San Francisco, California · 836,321 residents · 60 ZIP codes
EPA records show Nitrate detections in San Francisco, California water samples.
Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-06-04
Nitrate in San Francisco Tap Water
Nitrate has been detected in San Francisco, California drinking water at a maximum level of 7.48 ppb — below the EPA MCL of 10 mg/L (as nitrogen).
This analysis covers 836,321 residents across 60 ZIP codes in San Francisco.
San Francisco's overall water quality grade is C (55/100).
Is Nitrate in San Francisco Water Safe?
Nitrate was detected in San Francisco water but currently falls within EPA limits. However, some health organizations argue the EPA MCL may not be protective enough.
If you are concerned, a reverse osmosis or ion exchange filter can reduce nitrate levels further.
Nitrate Levels by ZIP Code
| ZIP Code | Nitrate Level | EPA Limit | Status |
|---|---|---|---|
| 94101 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94119 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94120 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94125 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94126 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94128 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94129 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94136 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94137 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94139 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94140 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94141 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94142 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94143 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94144 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94145 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94146 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94147 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94150 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94151 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94153 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94154 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94156 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94159 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| 94160 | 7.48 mg/L | 10 mg/L (as nitrogen) | OK |
| ...8 more ZIP codes |
Average nitrate level across San Francisco: 7.48 ppb
Health Effects of Nitrate
- Methemoglobinemia ("blue baby syndrome") in infants under 6 months
- Increased risk of colorectal and bladder cancer (long-term)
- Thyroid disease from chronic exposure
- Possible reproductive effects
Health risk severity: High. Governed by the National Primary Drinking Water Regulations.
How Nitrate Gets Into Drinking Water
- Agricultural fertilizer runoff
- Animal feedlot operations and manure
- Septic system leachate
- Urban stormwater and wastewater discharge
What to Do About Nitrate in San Francisco Water
- Reverse osmosis is the most effective method for nitrate removal
- Ion exchange systems designed for nitrate can also work
- Standard carbon filters do NOT remove nitrate
- Boiling water increases nitrate concentration — never boil for nitrate
Look for filters certified under NSF 53 / NSF 58 for nitrate removal.