Lake San Marcos Tap Water Quality Report
Lake San Marcos's water has 2 contaminants above EPA MCLGs. Consider using a certified water filter for additional protection.
Water system
VALLECITOS WD
People Served
108,392
Health-based violations since 2020
0
VALLECITOS WD. EPA SDWA violation data as of Q2 2026 (downloaded 2026-07-09).
Latest sample on file
May 2025 · VALLECITOS WD
Utilities publish newer results in their annual water quality report (Consumer Confidence Report).
Is Lake San Marcos Tap Water Safe to Drink?
We recommend using a certified water filter for additional protection, especially for vulnerable populations like children, pregnant women, and those with compromised immune systems. Lake San Marcos's water has 2 contaminants above EPA health-based guidelines (MCLGs), while it meets federal legal limits.
VALLECITOS WD, Lake San Marcos's water system, serves 108,392 people. Water quality testing is conducted regularly and reported to the EPA. The latest sample on file for VALLECITOS WD is from May 2025.
In EPA's 2023–2026 UCMR 5 testing, VALLECITOS WD measured lithium at up to 52 µg/L, which EPA counts as above its health reference level of 10 µg/L. That level is a screening value EPA uses to decide what to study further, not a legal limit, and this result does not change this page's water-quality summary.
Boil water advisories are issued by water systems and state agencies, and they change from day to day. Boil water advisories in California
Lake San Marcos Water Service Areas
What these numbers actually mean for Lake San Marcos, CA
We read Lake San Marcos, CA’s published record and send you a short report — which findings warrant a decision, which to ignore, and what to do about it. Including when the answer is nothing.
- 2 contaminants above EPA MCLGs
- 34 results on file
- 23 PFAS compounds on record
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Recommended Water Filters for Lake San Marcos
Based on Lake San Marcos's water quality data, these NSF-certified filters are recommended to remove contaminants above EPA MCLGs.
Culligan
ZeroWater
NSF Certified:
Flow Rate
1.9 gpm
Daily Production
1 gpd
Highlights:
- Compact design
- Easy to set up
- Affordable
- NSF-42, NSF-53, NSF-401 certified
Removes 19 contaminants:
+14 more
Strontium, Molybdenum, Fluoride, Uranium, Lead, Total PFAS, Chlorine, 25, Phosphorus, Bicarbonate, Calcium, Carbonate, Magnesium, Sodium
Santevia
Bath Filter
NSF Certified:
Flow Rate
0.36 gpm
Highlights:
- Organic cotton design reduces plastic used in construction
- Affordable upfront & ongoing cost
- The only bath filter that removed 100% chlorine with “normal” faster faucet flow
Removes 1 contaminants:
Waterdrop
A1
NSF Certified:
Flow Rate
1 gpm
Highlights:
- Performance certified
- Lower price than Philips
- Hot water dispensing
- Compact design
Removes 5 contaminants:
Whirlpool Corporation
W11256135
NSF Certified:
Capacity
1001 gal
Filter Life
3 mo
Flow Rate
0.7 gpm
Removes 19 contaminants:
+14 more
Benzene, Carbofuran, Chlorine (Free), Chlorine (Total), Chlorine Dioxide, Chlorobenzene, Cryptosporidium, Ethylbenzene, Lead, Mercury, Metolachlor, Tetrachloroethylene, Toxaphene, Turbidity
Filters for what Lake San Marcos reported
Test Your Water Quality
Professional laboratory testing provides accurate, detailed analysis of your drinking water.
SimpleLab
Advanced Home Water Test
$269
Comprehensive water analysis testing over 200 contaminants including bacteria, heavy metals, and chemical compounds.
Tap Score
Advanced Microplastics Test
$829
Cutting-edge testing for microplastics particles in drinking water using advanced laboratory techniques.
Tap Score
Haloacetic Acids (HAA9) Test
$275
Tests for disinfection byproducts formed when chlorine reacts with organic matter in water treatment.
What Lake San Marcos's water readings can explain
Utility-reported data for Lake San Marcos includes a chlorine-based disinfectant — the readings behind these common tap water questions. We publish a city-level hardness figure for Lake San Marcos, resolved from its water systems where they report one and estimated from county sampling where they do not. Each page starts with the hot-tap and cold-tap check, then shows what your own water system reported.
On a private well near Lake San Marcos? Public-water results do not apply to private wells. See San Diego County well water testing and USGS risk data — modeled arsenic, nitrate, and the tests to run.
Water softener cost and installation in Lake San Marcos
Lake San Marcos's tap water measures 9.9 grains per gallon (170.0 mg/L) — hard on the USGS scale, the range where scale on fixtures and appliances is the usual complaint.
Water softener cost for 9.9 gpg water in Lake San Marcos — equipment and local installation labour for your ZIP code, with the sizing arithmetic shown in full. For the national picture first, read what a water softener costs — equipment, installation labour and ten-year ownership, each separated out. For California as a whole, read water softener cost in California — priced against the plumber wage published for the state.
Frequently Asked Questions About Lake San Marcos Tap Water
Lake San Marcos's water has 2 contaminants above EPA MCLGs. While the water meets federal legal limits, we recommend using a certified water filter for additional protection, especially for vulnerable populations like children, pregnant women, and those with compromised immune systems.
Spotted something off on this page?
Residents keep our data honest.
This form corrects our data; it does not reach VALLECITOS WD. For a problem with your water now (discolored water, no water, low pressure, a leak), contact VALLECITOS WD directly.
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