Drinking water quality · 2024
· Verified
What's in Costa Mesa, CA tap water
37 contaminants were measured in the Costa Mesa, CA water system's 2024 annual report. Each is shown below against its federal limit — 2 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 37
- Over federal limit
- 2
- Approaching the limit
- 0
- Worst contaminant
- Specific Conductance
- Service area
- CA
Where your water comes from · EPA SDWIS
Costa Mesa, CA's drinking water comes from ground water, drawn from 2 sources.
Source
- WELL
- WELL 02
Treatment
Distribution
Historical readings · EPA Six-Year Review (2012–2019)
1 contaminant historically over EPA limits in Costa Mesa, CA
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
ARSENIC worst: 2014 | 0.03 mg/L 3.0× 2.3× the national p90 | 0.01 mg/L | '12'13'14'15 |
FLUORIDE worst: 2012 | 0.33 mg/L within | 4 mg/L | '12'17 |
NITRATE worst: 2013 | 0.678 mg/L within | 10 mg/L | '13 |
CHROMIUM worst: 2017 | 0.004 mg/L within below national p90 | 0.1 mg/L | '17 |
SELENIUM worst: 2017 | 0.001 mg/L within | 0.05 mg/L | '17 |
BARIUM worst: 2017 | 0.026 mg/L within below national p90 | 2 mg/L | '17 |
TOLUENE worst: 2014 | 0.00075 mg/L within | 1 mg/L | '14 |
COPPER worst: 2017 | 0.003 mg/L below national p90 | — | '17 |
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Specific ConductanceA measure of how well water conducts electricity, which tracks dissolved mineral content. | 996AverageWeymouth | 1MCL | At or above the limit |
| Total Dissolved SolidsTotal dissolved solids — the combined content of all dissolved minerals and salts. | 632 mg/LAverageWeymouth | 1 mg/LMCL | At or above the limit |
| OdorA measure of detectable smell in the water. | 1AverageDiemer | 3MCL | Within the limit |
| ColorA measure of visible tint in the water. | 2AverageDiemer | 15MCL | Within the limit |
| TurbidityA measure of cloudiness from suspended particles in the water. | 0.12 NTUAverageAverage Amount | 5 NTUMCL | Within the limit |
| AlkalinityA measure of the water's capacity to neutralize acids. | 143 mg/LAverageAverage Amount | None set | Detected — no federal limit |
| Bicarbonate | 163 mg/LAverageAverage Amount | None set | Detected — no federal limit |
| HardnessA measure of dissolved calcium and magnesium minerals. | 272 mg/LAverageWeymouth | None set | Detected — no federal limit |
| pHA measure of how acidic or basic the water is. | 8.2AverageDiemer | None set | Detected — no federal limit |
| TOCTotal organic carbon — a measure of organic material dissolved in the water. | 2.4 mg/LAverageDiemer | None set | Detected — no federal limit |
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorineA disinfectant added to drinking water to kill bacteria and viruses. | 2.11 mg/LAverageAverage Amount | 4 mg/LMCL | Within the limit |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| AluminumA common element sometimes used as a treatment coagulant. | 93 ug/LAverageWeymouth | 200 ug/LMCL | Within the limit |
| Chromium, HexavalentHexavalent chromium ('chromium-6') — the more toxic form of chromium. | 0.34 ug/LAverageAverage Amount | 10 ug/LMCL | Within the limit |
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | Not detected ug/L90th percentileAt the tap | 15 ug/LAction level | None detected |
| BoronA naturally occurring element from rock and soil. | 0.2 mg/LAverageAverage Amount | None set | Detected — no federal limit |
| CalciumA naturally occurring mineral that contributes to water hardness. | 68 mg/LAverageWeymouth | None set | Detected — no federal limit |
| LithiumA naturally occurring element found in some groundwater. | 22 ug/LAverageAverage Amount | None set | Detected — no federal limit |
| MagnesiumA naturally occurring mineral that contributes to water hardness. | 26 mg/LAverageWeymouth | None set | Detected — no federal limit |
| PotassiumA naturally occurring mineral from rock and soil. | 5 mg/LAverageWeymouth | None set | Detected — no federal limit |
| SodiumA naturally occurring salt component. | 105 mg/LAverageWeymouth | None set | Detected — no federal limit |
| Vanadium | 4.5 ug/LAverageAverage Amount | None set | Detected — no federal limit |
Inorganic chemicals
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TTHMTotal trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. | 19 ug/LAverageAverage Amount | 80 ug/LMCL | Within the limit |
| BromateA disinfection byproduct formed when bromide-containing water is treated with ozone. | 2 ug/LAverageWeymouth | 10 ug/LMCL | Within the limit |
| HAA5Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. | 3 ug/LAverageAverage Amount | 60 ug/LMCL | Within the limit |
| NDMA | Not detected ng/LRangeSystem-wide | 3 ng/LPublic health goal | None detected |
| ChlorateA byproduct that can form during disinfection, especially when hypochlorite solutions degrade. | 80 ug/LAverageWeymouth | None set | Detected — no federal limit |
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Gross Beta Particle ActivityGross beta particle activity — a combined measure of beta-emitting radioactive substances. | 4 pCi/LAverageDiemer | 50 pCi/LMCL | Within the limit |
| UraniumA naturally occurring radioactive metal from erosion of natural deposits. | 1 pCi/LAverageDiemer | 20 pCi/LMCL | Within the limit |
| Combined RadiumCombined radium-226 and radium-228 — naturally occurring radioactive elements. | Not detected pCi/LAverageAverage Amount | 5 pCi/LMCL | Within the limit |
| Gross AlphaGross alpha particle activity — a combined measure of alpha-emitting radioactive substances. | Not detected pCi/LAverageDiemer | 15 pCi/LMCL | Within the limit |
People also ask about Costa Mesa, CA's water
+Is Costa Mesa, CA tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Costa Mesa, CA water utility lists 2 contaminants at or above the federal limit: Specific Conductance and Total Dissolved Solids. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in Costa Mesa, CA tap water?
37 contaminants were measured in Costa Mesa, CA's 2024 Consumer Confidence Report, spanning metals, physical & aggregate, and disinfection byproducts. 24 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in Costa Mesa, CA tap water?
2 contaminants in Costa Mesa, CA's 2024 report sit at or above the federal limit: Specific Conductance (996.0× the limit); Total Dissolved Solids (632.0× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in Costa Mesa, CA tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is Specific Conductance, at 996.0× the federal threshold. It belongs to the physical & aggregate family of contaminants.
+Where does the data on this page come from?
Every value is transcribed from Costa Mesa, CA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is Costa Mesa, CA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.