Chromium-6 (Hexavalent Chromium) in Drinking Water —...
City of Watsonville · Freedom, CA · 65,231 people served
Data: EPA SDWIS, ECHO, 2024 Consumer Confidence Report
Chromium-6 (Hexavalent Chromium) Detected in City of Watsonville
Chromium-6 (Hexavalent Chromium) was detected at 196.3 ppb in the City of Watsonville water system serving Freedom, Watsonville (CA), exceeding the EPA limit of 100 ppb (total chromium MCL; no federal Cr-6 MCL).
This system serves approximately 65,231 people across 3 ZIP codes.
Data source: 2024 Consumer Confidence Report (CCR) and EPA SDWIS/ECHO.
Detected Levels
| Contaminant | Level Detected | EPA Limit | Status |
|---|---|---|---|
| Chromium | 196.3 ppb | 50 ppb | Exceeds Limit |
| Chromium, hexavalent | 8.9 ppb | 10 ppb | Within Limit |
Health Effects of Chromium-6 (Hexavalent Chromium)
Hexavalent chromium (chromium-6) is classified by the EPA as "likely to be carcinogenic to humans" when ingested. It is associated with increased risk of stomach and gastrointestinal cancers. Made famous by the Erin Brockovich case, chromium-6 was found contaminating drinking water in Hinkley, California. There is currently no federal MCL specific to chromium-6 — only a total chromium MCL of 100 ppb. California previously set a chromium-6 MCL of 10 ppb (withdrawn in 2017), and scientists have recommended levels as low as 0.02 ppb for safety.
Source: ATSDR — Chromium Toxicological Profile; EPA.
EPA Standard
The EPA maximum contaminant level (MCL) for chromium-6 is 100 ppb (total chromium MCL; no federal Cr-6 MCL), governed by the National Primary Drinking Water Regulations (total chromium). Water systems that exceed this limit must notify consumers and take corrective action.
What You Can Do
- Install a reverse osmosis system — the most effective household method for chromium-6 removal
- Strong-base anion exchange resins can also reduce chromium-6 levels
- Standard carbon filters do NOT remove chromium-6
- Have your water tested specifically for hexavalent chromium (Cr-6), not just total chromium
- Check the EWG Tap Water Database for chromium-6 data in your area
- If levels exceed California's former 10 ppb guideline, consider treatment even if below the federal MCL
Recommended Water Filters
The most effective treatment for chromium-6 removal is Reverse Osmosis or Strong-Base Anion Exchange.
| Filter Type | Effectiveness | NSF Standard | Notes |
|---|---|---|---|
| Reverse Osmosis (RO) | 95-99% | NSF 58 | Most effective household treatment for Cr-6 |
| Strong-Base Anion Exchange | 85-95% | NSF 53 | Effective but requires regular media replacement |
| Activated Alumina | 70-90% | NSF 53 | pH-dependent; works best at lower pH |
ZIP Codes Served by This System
Check water quality for your specific ZIP code:
Related Resources
- City of Watsonville — Full Water System Profile
- Chromium-6 (Hexavalent Chromium) in Drinking Water — Overview
- EPA: Chromium-6 (Hexavalent Chromium)
Detected Levels
| Contaminant | Level Detected | EPA Limit | Status |
|---|---|---|---|
| Chromium | 196.3 ppb | 50 ppb | Exceeds Limit |
| Chromium, hexavalent | 8.9 ppb | 10 ppb | Within Limit |
Recommended Water Filters
The most effective treatment for chromium-6 removal is Reverse Osmosis or Strong-Base Anion Exchange.
| Filter Type | Effectiveness | NSF Standard | Notes |
|---|---|---|---|
| Reverse Osmosis (RO) | 95-99% | NSF 58 | Most effective household treatment for Cr-6 |
| Strong-Base Anion Exchange | 85-95% | NSF 53 | Effective but requires regular media replacement |
| Activated Alumina | 70-90% | NSF 53 | pH-dependent; works best at lower pH |