Water Quality Report · Updated May 12, 2026
CARLSBAD MWD
CARLSBAD MWD delivers tap water graded F (53/100) by TapWaterSafety.org. The utility serves approximately 95,158 residents in CARLSBAD, California using surface water (purchased). The most significant water quality concerns are: PFAS contamination; Arsenic* significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline. For questions, the utility can be reached at 442-339-2722.
Is CARLSBAD tap water safe to drink?
CARLSBAD MWD delivers tap water that earns a grade of F (53/100) from TapWaterSafety.org — a poor rating, with significant contamination concerns and/or recent violations.
The utility serves 95,158 residents in CARLSBAD, drawing from surface water (purchased).
Public testing data identifies 16 contaminants in this water above EWG's health-based guidelines, including: Arsenic*, Haloacetic acids (HAA5), Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Bromodichloromethane, Dibromochloromethane, Dibromoacetic acid, Bromate*, Chloroform, Dichloroacetic acid, Chromium (hexavalent), Trichloroacetic acid, Uranium*, Bromochloromethane, Bromoform, Nitrate*. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for CARLSBAD residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for CARLSBAD MWD.
PFAS contamination
Severe concernPerfluorooctane sulfonate (PFOS)* detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
Arsenic* significantly above health guideline
Moderate concernArsenic* detected at 1.49 ppb, 373x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 36.2 ppb, 362x above the EWG health guideline of 0.1 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 14.3 ppb, 239x above the EWG health guideline of 0.06 ppb.
Contact CARLSBAD MWD
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for CARLSBAD
Filters matched to the specific contaminants in this water supply.
Reverse Osmosis or NSF P473 certified carbon
$80-$750Activated carbon and RO are the only technologies proven to remove PFAS at certified levels.
Reverse Osmosis
$249-$750Arsenic is most effectively removed by reverse osmosis. Some specialized adsorptive filters also work.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 53/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Arsenic* Heavy metal |
1.49 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 373× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
14.3 ppb | 0.06 | — | — | — | — | — | 239× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
14.0 ppb | 0.15 | 80.0 | 100 | — | — | — | 93× over |
| Bromodichloromethane Disinfection byproduct |
4.23 ppb | 0.06 | — | — | — | — | — | 70× over |
| Dibromochloromethane Disinfection byproduct |
4.19 ppb | 0.1 | — | — | — | — | — | 42× over |
| Dibromoacetic acid Disinfection byproduct |
0.773 ppb | 0.03 | — | — | — | — | — | 26× over |
| Bromate* Disinfection byproduct |
2.39 ppb | 0.1 | 10.0 | 10 | 10 | 0.1 | — | 24× over |
| Chloroform Disinfection byproduct |
3.91 ppb | 0.4 | — | — | — | — | — | 9.8× over |
| Dichloroacetic acid Disinfection byproduct |
1.22 ppb | 0.2 | — | — | — | — | — | 6.1× over |
| Chromium (hexavalent) Heavy metal |
0.101 ppb | 0.02 | — | — | — | — | — | 5.1× over |
| Trichloroacetic acid Disinfection byproduct |
0.486 ppb | 0.1 | — | — | — | — | — | 4.9× over |
| Uranium* Radiological |
1.68 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 3.9× over |
| Bromochloromethane Other |
0.19 ppb | 0.06 | — | — | — | — | — | 3.2× over |
| Bromoform Disinfection byproduct |
1.55 ppb | 0.5 | — | — | — | — | — | 3.1× over |
| Nitrate* Inorganic |
0.145 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 1.0× over |
| Perfluorooctane sulfonate (PFOS)* PFAS |
0.25 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | Below guideline |
| Chlorate Disinfection byproduct |
168.8 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Nitrate and nitrite* Inorganic |
0.04 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| Molybdenum Other |
3.8 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Barium* Heavy metal |
60.6 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Vanadium Other |
1.3 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Aluminum* Heavy metal |
37.0 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Manganese Heavy metal |
1.67 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.0291 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.834 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA)* PFAS |
0.275 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Bromide* Other |
160.7 ppb | — | — | — | — | — | — | Below guideline |
| Fluoride* Inorganic |
0.578 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Lithium Other |
24.5 ppb | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
CARLSBAD MWD service area
This water system serves 1 community in San Diego County, California. Click any city for its dedicated tap water quality page.
Find the right filter for CARLSBAD water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.