Clearlake Tap Water Quality Report
Clearlake's water has 1 contaminant above EPA MCLGs. Consider using a certified water filter for additional protection.
No single water system serves most of Clearlake (16,636 residents, Census 2024 estimate). Its large systems are HIGHLANDS MUTUAL WATER COMPANY (EPA counts 9,510 people served, about 57% of Clearlake's population); KONOCTI COUNTY WATER DISTRICT (EPA counts 5,928 people served, about 36% of Clearlake's population); GOLDEN STATE WATER CO.-CLEARLAKE SYSTEM (EPA counts 4,713 people served, about 28% of Clearlake's population). EPA's counts may include people served outside Clearlake, so each share is at most that. Check which one bills you: each system's figures are shown separately below.
- HIGHLANDS MUTUAL WATER COMPANY: 211 contaminants tested, 1 above EPA MCLGs; health-based violations since 2020: 2
- KONOCTI COUNTY WATER DISTRICT: 194 contaminants tested, 1 above EPA MCLGs; health-based violations since 2020: 0
- GOLDEN STATE WATER CO.-CLEARLAKE SYSTEM: 69 contaminants tested, 1 above EPA MCLGs; health-based violations since 2020: 0
Other systems listed for Clearlake with results above guidelines: KONOCTI COUNTY WATER DISTRICT (1 above guidelines), WINDFLOWER POINT MUTUAL WATER COMPANY (2 above guidelines), GOLDEN STATE WATER CO.-CLEARLAKE SYSTEM (1 above guidelines)
Water systems
3 large systems
Residents (Census 2024)
16,636
Health-based violations since 2020
2
HIGHLANDS MUTUAL WATER COMPANY. EPA SDWA violation data as of Q2 2026 (downloaded 2026-07-09).
Latest sample on file
Mar 2023 · HIGHLANDS MUTUAL WATER COMPANY
Utilities publish newer results in their annual water quality report (Consumer Confidence Report).
Is Clearlake 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. Clearlake's water has 1 contaminant above EPA health-based guidelines (MCLGs).
HIGHLANDS MUTUAL WATER COMPANY, Clearlake's water system, serves 9,510 people. 4 other systems are listed for Clearlake. Each system's results are listed under its own name, never added to HIGHLANDS MUTUAL WATER COMPANY's. Water quality testing is conducted regularly and reported to the EPA. The latest sample on file for HIGHLANDS MUTUAL WATER COMPANY is from Mar 2023.
In EPA's 2023–2026 UCMR 5 testing, HIGHLANDS MUTUAL WATER COMPANY measured lithium at up to 25 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
Clearlake Water Service Areas
What these numbers actually mean for Clearlake, CA
We read Clearlake, 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.
- 1 contaminant above EPA MCLGs and 8 contaminants with an EPA health goal detected in some samples (no level on file)
- 124 results on file
- 23 PFAS compounds on record
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Recommended Water Filters for Clearlake
Based on Clearlake'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
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 Clearlake's water readings can explain
Utility-reported data for Clearlake includes sulfate and a chlorine-based disinfectant — the readings behind these common tap water questions. We publish a city-level hardness figure for Clearlake, 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 Clearlake? Public-water results do not apply to private wells. See Lake County well water testing and USGS risk data — modeled arsenic, nitrate, and the tests to run.
Water softener cost and installation in Clearlake
Clearlake's tap water measures 5.2 grains per gallon (88.6 mg/L) — moderately hard on the USGS scale, below the range where scale is usually worth treating.
Water softener cost for 5.2 gpg water in Clearlake — 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 Clearlake Tap Water
Clearlake's water has 1 contaminant above EPA MCLGs. 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 HIGHLANDS MUTUAL WATER COMPANY. For a problem with your water now (discolored water, no water, low pressure, a leak), contact HIGHLANDS MUTUAL WATER COMPANY directly.
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