Nitrate in Hollister, CA Drinking Water
Nitrate data for Hollister, California · 52,365 residents · 2 ZIP codes
Water quality records for Hollister, California show Nitrate detections on file — a finding that places it among the contaminants worth tracking for this area.
Data: EPA SDWIS, CCR Reports, ECHO Last verified: 2026-05-14
Nitrate in Hollister Tap Water
Nitrate has been detected in Hollister, California drinking water at a maximum level of 28 ppb — below the EPA MCL of 10 mg/L (as nitrogen).
This analysis covers 52,365 residents across 2 ZIP codes in Hollister.
Hollister's overall water quality grade is C (64/100).
Is Nitrate in Hollister Water Safe?
Nitrate was detected in Hollister 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 |
|---|---|---|---|
| 95023 | 28 ppm | 10 mg/L (as nitrogen) | OK |
| 95024 | 28 ppm | 10 mg/L (as nitrogen) | OK |
Average nitrate level across Hollister: 28 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 Hollister 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.