Lake St. Louis Tap Water Quality Report
Lake St. Louis's water has 4 contaminants above EPA MCLGs. We recommend using a certified water filter.
Other systems listed for Lake St. Louis with results above guidelines: ST CHARLES CO PWSD #2 WRIGHT CITY (1 above guidelines)
People Served
100,587
Health-based violations since 2020
0
ST CHARLES COUNTY PWSD 2. EPA SDWA violation data as of Q2 2026 (downloaded 2026-07-09).
Latest sample on file
Oct 2025 · ST CHARLES COUNTY PWSD 2
Utilities publish newer results in their annual water quality report (Consumer Confidence Report).
Is Lake St. Louis Tap Water Safe to Drink?
We strongly recommend using a certified water filter to reduce exposure: Lake St. Louis's water has 4 contaminants above EPA health-based guidelines. Check our filter recommendations below for NSF-certified options that can remove the specific contaminants found in Lake St. Louis's water.
ST CHARLES COUNTY PWSD 2, Lake St. Louis's water system, serves 100,587 people. 1 other system is listed for Lake St. Louis. Each system's results are listed under its own name, never added to ST CHARLES COUNTY PWSD 2's. Water quality testing is conducted regularly and reported to the EPA. The latest sample on file for ST CHARLES COUNTY PWSD 2 is from Oct 2025.
In EPA's 2023–2026 UCMR 5 testing, ST CHARLES COUNTY PWSD 2 measured lithium at up to 47.5 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 Missouri
Lake St. Louis Water Service Areas
What these numbers actually mean for Lake St. Louis, MO
We read Lake St. Louis, MO’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.
- 4 contaminants above EPA MCLGs and 5 contaminants with an EPA health goal detected in some samples (no level on file)
- 202 results on file
- 23 PFAS compounds on record
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Recommended Water Filters for Lake St. Louis
Based on Lake St. Louis's water quality data, these NSF-certified filters are recommended to remove contaminants above EPA MCLGs.
Solventum Purification Inc.
3MRO401
NSF Certified:
Daily Production
11.48 gpd
Highlights:
- NSF-58 certified reverse osmosis system
- 11.48 GPD production capacity
- Reduces total dissolved solids (TDS) for purer water
Removes 15 contaminants:
+10 more
Copper, Cryptosporidium, Fluoride, Lead, Radium 226, Radium 228, Radium, combined (-226 & -228), Selenium, Total Dissolved Solids, Turbidity
Solventum Purification Inc.
3MRO301
NSF Certified:
Daily Production
11.48 gpd
Highlights:
- NSF-58 certified reverse osmosis system
- 11.48 GPD production capacity
- Reduces total dissolved solids (TDS) for purer water
Removes 15 contaminants:
+10 more
Copper, Cryptosporidium, Fluoride, Lead, Radium 226, Radium 228, Radium, combined (-226 & -228), Selenium, Total Dissolved Solids, Turbidity
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:
Verify Your Water Quality with Independent Testing
With 4 contaminants above EPA MCLGs and 5 contaminants with an EPA health goal detected in some samples (no level on file), independent laboratory testing provides a second opinion and can track changes over time.
SimpleLab
Advanced Home Water Test
$269
Comprehensive water analysis testing over 200 contaminants including bacteria, heavy metals, and chemical compounds.
Tap Score
Haloacetic Acids (HAA9) Test
$275
Tests for disinfection byproducts formed when chlorine reacts with organic matter in water treatment.
Tap Score
Advanced Microplastics Test
$829
Cutting-edge testing for microplastics particles in drinking water using advanced laboratory techniques.
With 4 contaminants above health guidelines, you may want to explore water purification options. Learn how to make distilled water at home for applications like humidifiers, CPAP machines, and baby formula.
What Lake St. Louis's water readings can explain
Utility-reported data for Lake St. Louis includes iron, manganese and sulfate — the readings behind these common tap water questions. We publish a city-level hardness figure for Lake St. Louis, 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 St. Louis? Public-water results do not apply to private wells. See St. Charles County well water testing and USGS risk data — modeled arsenic, nitrate, and the tests to run.
Water softener cost and installation in Lake St. Louis
Lake St. Louis's tap water measures 6.9 grains per gallon (118.0 mg/L) — moderately hard on the USGS scale, below the range where scale is usually worth treating.
Water softener cost for 6.9 gpg water in Lake St. Louis — 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 Missouri as a whole, read water softener cost in Missouri — priced against the plumber wage published for the state.
Frequently Asked Questions About Lake St. Louis Tap Water
Lake St. Louis's water has 4 contaminants above EPA MCLGs. We strongly recommend using a certified water filter to reduce exposure to these contaminants. Check our filter recommendations below for NSF-certified options that can remove the specific contaminants found in Lake St. Louis's water.
Spotted something off on this page?
Residents keep our data honest.
This form corrects our data; it does not reach ST CHARLES COUNTY PWSD 2. For a problem with your water now (discolored water, no water, low pressure, a leak), contact ST CHARLES COUNTY PWSD 2 directly.
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