Thornton Tap Water Quality Report
Thornton's water has 6 contaminants above EPA MCLGs. We recommend using a certified water filter.
Other systems listed for Thornton with results above guidelines: PINE LAKES RANCH (3 above guidelines), DENVER WATER BOARD (2 above guidelines), HOLIDAY HILLS VILLAGE (3 above guidelines)
People Served
155,700
Health-based violations since 2020
0
THORNTON CITY OF. EPA SDWA violation data as of Q2 2026 (downloaded 2026-07-09).
Latest sample on file
Jul 2025 · THORNTON CITY OF
Utilities publish newer results in their annual water quality report (Consumer Confidence Report).
Is Thornton Tap Water Safe to Drink?
We strongly recommend using a certified water filter to reduce exposure: Thornton's water has 6 contaminants above EPA health-based guidelines. Check our filter recommendations below for NSF-certified options that can remove the specific contaminants found in Thornton's water.
THORNTON CITY OF, Thornton's water system, serves 155,700 people. 3 other systems are listed for Thornton. Each system's results are listed under its own name, never added to THORNTON CITY OF's. Water quality testing is conducted regularly and reported to the EPA. The latest sample on file for THORNTON CITY OF is from Jul 2025.
In EPA's 2023–2026 UCMR 5 testing, THORNTON CITY OF measured lithium at up to 34 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 Colorado
Thornton Water Service Areas
What these numbers actually mean for Thornton, CO
We read Thornton, CO’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.
- 6 contaminants above EPA MCLGs and 11 contaminants with an EPA health goal detected in some samples (no level on file)
- 154 results on file
- 23 PFAS compounds on record
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Recommended Water Filters for Thornton
Based on Thornton'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
AquaTru
Classic
NSF Certified:
Flow Rate
0.04 gpm
Daily Production
600 gpd
Highlights:
- Best overall contaminant reduction score
- Most performance certifications
- Lifetime warranty
- NSF-42, NSF-53, NSF-58, NSF-401 certified
Removes 23 contaminants:
+18 more
Molybdenum, Barium, Chlorine, Arsenic, 83+ contaminants, Calcium, Chloride, Copper, Magnesium, Nitrate, Phosphorus, Sodium, Sulfate, Total Dissolved Solids, Zinc, Total THMs, Chloroform, Nitrate (as N)
AquaTru
Carafe
NSF Certified:
Flow Rate
0.3 gpm
Daily Production
4 gpd
Highlights:
- Verified PFAS reduction
- Glass collection vessel
- Plug-and-play installation
- NSF-53, NSF-42, NSF-58, NSF-401, NSF-372 certified
Removes 17 contaminants:
+12 more
Arsenic, 83+ contaminants, Copper, Total THMs, Chloroform, Chloride, Sulfate, Nitrate (as N), Molybdenum, Barium, Strontium, Uranium
Waterdrop
A1
NSF Certified:
Flow Rate
0.042 gpm
Daily Production
130 gpd
Highlights:
- Built-in UV sterilization
- Easy maintenance with filter change reminders
- NSF-58 certified
- Hot and cold water dispensing
Removes 12 contaminants:
+7 more
Molybdenum, Sulfate, Strontium, Phosphorus, Chlorine, Barium, Nitrate
Verify Your Water Quality with Independent Testing
With 6 contaminants above EPA MCLGs and 11 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
PFAS Forever Chemicals Test
$339.95
Specialized test for PFOA, PFOS, and 24 other forever chemicals. Essential for areas near military bases, airports, or industrial sites.
Tap Score
Haloacetic Acids (HAA9) Test
$275
Tests for disinfection byproducts formed when chlorine reacts with organic matter in water treatment.
With 6 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 Thornton's water readings can explain
Utility-reported data for Thornton includes a chlorine-based disinfectant — the readings behind these common tap water questions. We publish a city-level hardness figure for Thornton, 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 Thornton? Public-water results do not apply to private wells. See Adams County well water testing and USGS risk data — modeled arsenic, nitrate, and the tests to run.
Water softener cost and installation in Thornton
Thornton's tap water measures 7.0 grains per gallon (119.0 mg/L) — moderately hard on the USGS scale, below the range where scale is usually worth treating.
Water softener cost for 7.0 gpg water in Thornton — 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 Colorado as a whole, read water softener cost in Colorado — priced against the plumber wage published for the state.
Frequently Asked Questions About Thornton Tap Water
Thornton's water has 6 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 Thornton's water.
Spotted something off on this page?
Residents keep our data honest.
This form corrects our data; it does not reach THORNTON CITY OF. For a problem with your water now (discolored water, no water, low pressure, a leak), contact THORNTON CITY OF directly.
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