Costa Mesa · Orange County · tap water report
Costa Mesa tap water grades A: 0 over the legal limit, 0 above the health guideline. Plain-English report and a free home water test.
Grade A: Passing grade. Every measured chemical sits well inside the safe range.
| Chemical | Measured | Legal limit | Verdict |
|---|---|---|---|
| Hardness (as CaCO3) | 230 mg/L (13.5 grains per gallon) | no health limit | Very hard |
| Chlorine byproducts | 21 ppb | 80 ppb | Good |
| Chlorine byproducts (HAA5) | 10 ppb | 60 ppb | Good |
| Chlorine | 1.6 ppm | 4 ppm | Good |
| Color (color units) | 1 color units | 15 color units (taste standard) | Good |
| Odor (threshold odor number) | 1 TON | 3 TON (taste standard) | Good |
| Turbidity | 0.1 NTU | 5 NTU (taste standard) | Good |
| Copper | 0.2 ppm | 1.3 ppm | Good |
| Arsenic | 2.1 ppb | 10 ppb | Good |
| Nitrate | 3.5 ppm | 10 ppm | Good |
| Fluoride | 0.5 ppm | 2 ppm | Good |
| Total Dissolved Solids (TDS) | 470 mg/L | 1000 mg/L (taste standard) | Good |
| Chloride | 82 mg/L | 500 mg/L (taste standard) | Good |
| Sulfate | 40 mg/L | 500 mg/L (taste standard) | Good |
| Alkalinity (as CaCO3) | 160 mg/L | none set | Good |
| Electrical Conductivity | 780 µS/cm | 1600 µS/cm (taste standard) | Good |
How to read the verdicts: Good means the measurement sits under half of the federal legal limit. Caution means it is legal but at or above half the limit, the range where health researchers advise staying lower. Too high means it exceeded the legal limit. Taste standards are EPA secondary limits for taste and appearance. Hardness uses the USGS scale, where anything over 180 mg/L counts as very hard. When a utility blends water from wells and imported supplies, the same chemical can appear twice with each source's result.
5 measured results on file across every sampling period the EPA publishes.
Mesa Water District (PWSID CA3010004) has 2 violations in the EPA Safe Drinking Water Information System, 0 of them health-based.
Every measured chemical in the latest utility tests sits well inside the safe range, and Mesa Water District reports 0 health-based violations to the EPA.
Mesa Water District's most recent Lead and Copper Rule result, from the 2024 to 2026 monitoring period, found no detectable lead at the 90th percentile of tested homes. The federal action level is 0.015 mg/L, so the system result sits under it. Lead usually enters water from a home's own pipes and fixtures, so a single house can differ from the system figure.
The EPA record lists 2 violations for this system, 0 of them health-based. The rest are monitoring and reporting notes.
Mesa Water District serves about 110,000 people in Orange County and relies mainly on surface water. It is public water system CA3010004.
Text 949-414-9944 for a free water test. A local FilteredWTR tech screens the water at your own faucet for hardness, chlorine and sediment and explains each reading while you watch. The visit is free, and afterward the decision stays yours.
A local FilteredWTR tech screens the water at your faucet for hardness, chlorine and sediment and explains each reading while you watch. The visit is free, and afterward the decision stays yours.
The fix for Costa Mesa water · Where Costa Mesa's water comes from · Whole-home water treatment explained · Orange County · All cities