Water Quality Report · Updated October 07, 2026
OLIVENHAIN MWD
OLIVENHAIN MWD delivers tap water graded D (63/100) by TapWaterSafety.org. The utility serves approximately 86,458 residents in ENCINITAS, California using surface water (purchased). The most significant water quality concerns are: Arsenic significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. For questions, the utility can be reached at 760-753-6466.
Is ENCINITAS tap water safe to drink?
OLIVENHAIN MWD delivers tap water that earns a grade of D (63/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including arsenic significantly above health guideline.
The utility serves 86,458 residents in ENCINITAS, drawing from surface water (purchased).
Public testing data identifies 13 contaminants in this water above EWG's health-based guidelines, including: Arsenic, Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Bromodichloromethane, Dibromochloromethane, Dibromoacetic acid, Trichloroacetic acid, Chloroform, Dichloroacetic acid, Bromoform, Uranium, Chromium (hexavalent). 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.
EPA compliance record
Official U.S. EPA records for OLIVENHAIN MWD (system ID CA3710029) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Quick actions for ENCINITAS residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for OLIVENHAIN MWD.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 2.8 ppb, 700x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 28.0 ppb, 467x above the EWG health guideline of 0.06 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.
Contact OLIVENHAIN 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 ENCINITAS
Filters matched to the specific contaminants in this water supply.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
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 63/100 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 |
2.8 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 700× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
28.0 ppb | 0.06 | — | — | — | — | — | 467× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
36.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 362× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
33.9 ppb | 0.15 | 80.0 | 100 | — | — | — | 226× over |
| Bromodichloromethane Disinfection byproduct |
10.5 ppb | 0.06 | — | — | — | — | — | 175× over |
| Dibromochloromethane Disinfection byproduct |
10.2 ppb | 0.1 | — | — | — | — | — | 102× over |
| Dibromoacetic acid Disinfection byproduct |
1.66 ppb | 0.03 | — | — | — | — | — | 55× over |
| Trichloroacetic acid Disinfection byproduct |
3.43 ppb | 0.1 | — | — | — | — | — | 34× over |
| Chloroform Disinfection byproduct |
10.1 ppb | 0.4 | — | — | — | — | — | 25× over |
| Dichloroacetic acid Disinfection byproduct |
4.54 ppb | 0.2 | — | — | — | — | — | 23× over |
| Bromoform Disinfection byproduct |
3.15 ppb | 0.5 | — | — | — | — | — | 6.3× over |
| Uranium Radiological |
1.34 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 3.1× over |
| Chromium (hexavalent) Heavy metal |
0.0364 ppb | 0.02 | — | — | — | — | — | 1.8× over |
| Chlorate Disinfection byproduct |
174.3 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Bromochloromethane Other |
0.0347 ppb | 0.06 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
110.0 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Molybdenum Other |
3.81 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Vanadium Other |
1.73 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.814 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Strontium Radiological |
0.8 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.658 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Lithium Other |
50.2 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.
OLIVENHAIN 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 ENCINITAS water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.