Water Quality Report · Updated October 07, 2026
VALLECITOS WD
VALLECITOS WD delivers tap water graded D (55/100) by TapWaterSafety.org. The utility serves approximately 113,500 residents in SAN MARCOS, 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 760-744-0460.
Is SAN MARCOS tap water safe to drink?
VALLECITOS WD delivers tap water that earns a grade of D (55/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including pfas contamination.
The utility serves 113,500 residents in SAN MARCOS, drawing from surface water (purchased).
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Arsenic*, Haloacetic acids (HAA5), Haloacetic acids (HAA9), Total trihalomethanes (TTHMs), Bromodichloromethane, Dibromoacetic acid, Dibromochloromethane, Bromate*, Chloroform, Dichloroacetic acid, Trichloroacetic acid, Bromoform, Uranium*, Chromium (hexavalent), 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.
EPA compliance record
Official U.S. EPA records for VALLECITOS WD (system ID CA3710002) for the last 3 years. Checked 2026-10-07.
| Rule | Type | Since | Status |
|---|---|---|---|
| Lead and Copper Rule Revisions | Missed reporting | 07/02/2025 | Open |
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 SAN MARCOS residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for VALLECITOS WD.
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 10.3 ppb, 171x above the EWG health guideline of 0.06 ppb.
Contact VALLECITOS WD
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Recommended water filters for SAN MARCOS
Filters matched to the specific contaminants in this water supply.
Filter certified for PFOA/PFOS (NSF/ANSI 53 or 58)
$180-$750Reverse osmosis and some carbon block filters reduce PFAS. Look for certification to NSF/ANSI 53 or 58 for PFOA/PFOS.
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 55/100 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 |
10.3 ppb | 0.06 | — | — | — | — | — | 171× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
21.9 ppb | 0.15 | 80.0 | 100 | — | — | — | 146× over |
| Bromodichloromethane Disinfection byproduct |
6.51 ppb | 0.06 | — | — | — | — | — | 108× over |
| Dibromoacetic acid Disinfection byproduct |
1.89 ppb | 0.03 | — | — | — | — | — | 63× over |
| Dibromochloromethane Disinfection byproduct |
6.07 ppb | 0.1 | — | — | — | — | — | 61× over |
| Bromate* Disinfection byproduct |
2.39 ppb | 0.1 | 10.0 | 10 | 10 | 0.1 | — | 24× over |
| Chloroform Disinfection byproduct |
6.46 ppb | 0.4 | — | — | — | — | — | 16× over |
| Dichloroacetic acid Disinfection byproduct |
3.09 ppb | 0.2 | — | — | — | — | — | 15× over |
| Trichloroacetic acid Disinfection byproduct |
1.49 ppb | 0.1 | — | — | — | — | — | 15× over |
| Bromoform Disinfection byproduct |
2.79 ppb | 0.5 | — | — | — | — | — | 5.6× over |
| Uranium* Radiological |
1.68 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 3.9× over |
| Chromium (hexavalent) Heavy metal |
0.0638 ppb | 0.02 | — | — | — | — | — | 3.2× 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 |
106.1 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Nitrate and nitrite* Inorganic |
0.04 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| Manganese Heavy metal |
13.5 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Molybdenum Other |
4.14 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Barium* Heavy metal |
60.6 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Aluminum* Heavy metal |
37.0 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Vanadium Other |
0.188 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.0406 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.05 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.994 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 |
13.3 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.
VALLECITOS WD 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 SAN MARCOS water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.