Chromium-6 (Hexavalent Chromium) in Drinking Water - Mesa Water District, CA
Mesa Water District · Costa Mesa, CA · 110,000 people served
Data: EPA SDWIS, ECHO, 2024 Consumer Confidence Report
Chromium-6 (Hexavalent Chromium) Data for Mesa Water District
In the pinned CCR corpus used for this correction, the matched entries support one comparable condition-level measurement: 800 ppb against a reported reference of 10 ppb. Source violation flags are shown separately below.
Matched Source Entries
| Contaminant | Reported Level | Reported MCL | Reported Unit | Source Violation Flag | Review Status |
|---|---|---|---|---|---|
| Hexavalent Chromium | 800 | 10 | ppb | true | Comparable entry |
Source violation flags are preserved as reported fields and have not been independently reconciled.
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 California previously set a chromium-6 MCL of 10 ppb (withdrawn in 2017), and scientists have recommended levels as low as 0.02 ppb for safety.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
- Mesa Water District — 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 |
|---|---|---|---|
| Hexavalent Chromium | 800 ppb | 10 ppb | Violation |
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 |