Nitrate in San Marino, CA Drinking Water
Nitrate data for San Marino, California · 12,464 residents · 2 ZIP codes
ZipCheckup's reading of Nitrate in San Marino, California: the highest detected level is 7.5 ppb; the EPA limit is 10 mg/L (as nitrogen). Nitrate carries a high health-risk designation.
Over the past reporting period, water systems in San Marino, California have recorded Nitrate at detectable concentrations in EPA compliance samples.
Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-07-13
Nitrate in San Marino Tap Water
Nitrate has been detected in San Marino, California drinking water at a maximum level of 7.5 ppm — below the EPA MCL of 10 mg/L (as nitrogen).
This analysis covers 12,464 residents across 2 ZIP codes in San Marino.
San Marino's overall water quality grade is B (75/100).
Is Nitrate in San Marino Water Safe?
Nitrate was detected in San Marino 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 |
|---|---|---|---|
| 91108 | 7.5 ppm | 10 mg/L (as nitrogen) | OK |
Average nitrate level across San Marino: 7.5 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 Marino 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.