Denver Drinking Water Quality
What's Really in Your Tap Water?
Good news for Denver residents — your tap water meets all current EPA drinking water standards. At 368 ppm (21.5 gpg), the water is quite hard — you may notice mineral buildup on fixtures. Lead levels test well below the EPA action level. There have been 6 violations recorded over the past 3 years.
Safe to Drink
Meets all EPA standards
21.5 GPG hardness
Lead
Below EPA action level
EPA action level: 15 ppb
Hardness
Very Hard water
US Average: 100 ppm
Is Denver Tap Water Safe to Drink?
Denver tap water meets all current EPA drinking water standards.
9 contaminants were tested in Denver's water. 7 were detected — all within EPA limits.
Metals — 1 contaminant detected, all within EPA limits. Highest: Barium at 0.0399 ppm (2% of EPA limit).
Disinfection Byproducts — 2 contaminants detected, all within EPA limits. Highest: Total Trihalomethanes (TTHM) at 37.9 ppb (47% of EPA limit).
Inorganic Chemicals — 2 contaminants detected, all within EPA limits. Highest: Fluoride at 0.675 ppm (17% of EPA limit).
PFAS "Forever Chemicals" — No PFAS "forever chemicals" were detected in available test data.
The data below shows test results from 3 water utilities serving 1.3M people in the Denver area.
Based on publicly available data from Denver Water 2025 Water Quality Report (2024). Water quality can vary by location, building plumbing, and over time. This assessment reflects compliance with federal EPA standards and is not medical advice.
Do I Need a Water Filter?
With very hard water (368 ppm), a water softener can reduce scale buildup in pipes, appliances, and water heaters.
How Hard is Denver Water?
368 ppm
21.5 grains per gallon
Very hard water causes significant mineral buildup. A water softener is recommended.
Impact on Your Home
Shower
Dries out skin & hair
Kitchen
Heavy mineral deposits
Laundry
Stiff, dingy clothes
Appliances
Significant scale
Regional Comparison
Values in ppm (mg/L as CaCO₃)
Do I Need a Water Softener?
At 368 ppm, Denver has very hard water. A water softener can help prevent scale buildup in water heaters, dishwashers, and pipes. According to the Water Quality Research Foundation, hard water can reduce appliance efficiency and increase energy costs. A whole-house water softener or salt-free conditioner can help.
Range: 48–116 ppm
Based on 209 samples from Denver Water 2025 Water Quality Report (2024)
Your pipes tell a different story
The data above shows what leaves the treatment plant—not what comes out of your faucet. Old pipes, lead solder, and building plumbing can add contaminants the city never tests for. Know exactly what's in your Denver tap water.
Home test kits detect lead, bacteria, pesticides, and 100+ other contaminants. Results in 5-10 business days from certified labs.
Lead & Contaminants
Understanding lead levels and water quality violations in Denver
Lead Test Results
90th Percentile Lead Level
3.59 ppb
Denver lead levels are well below the EPA action level.
Regular testing is still recommended, as lead can enter water through household plumbing.
Last sampled: 2024-12-31
About Lead in Drinking Water
What is Lead in Water?
According to the EPA, lead is a toxic metal that can dissolve into drinking water from older pipes, solder, and fixtures. It's invisible, tasteless, and odorless, making testing the only way to detect it. The EPA has set an action level of 15 ppb and states there is no safe level of lead exposure.
Potential Health Effects
According to the CDC: developmental delays, learning difficulties, lower IQ, behavioral issues
According to the EPA: high blood pressure, kidney damage, reproductive issues
How to Reduce Exposure
- •Run water for 30 seconds to 2 minutes before drinking, especially in the morning
- •Use cold water for cooking and drinking (hot water dissolves more lead)
- •Install a NSF-certified filter designed to remove lead
- •Test your water, especially if your home was built before 1986
PFAS “Forever Chemicals”
No PFAS detected in available test data
PFAS are synthetic chemicals that don't break down in the environment. No PFAS were detected in available test data.
Total Trihalomethanes (TTHM)
47% of EPA limit
Range: 16.4–64.7 ppb
Haloacetic Acids (HAA5)
38% of EPA limit
Range: 7.7–37.2 ppb
Fluoride
17% of EPA limit
Range: 0–0.93 ppm
Barium
2% of EPA limit
Range: 0.0173–0.0499 ppm
Other Detected Contaminants
9 contaminants detected
| Contaminant | Your Water | Limit (MCL) | Status |
|---|---|---|---|
Fluoride | 0.675 ppm Range: 0-0.93 Highest average across 4 treatment plants (Foothills) | 4 ppm Goal: 4 ppm | Safe 17% of limit |
Nitrate (as N) | 0.119 ppm Range: 0-0.167 Highest average across 4 treatment plants (Marston) | 10 ppm Goal: 10 ppm | Safe 1% of limit |
Barium | 0.0399 ppm Range: 0.0173-0.0499 | 2 ppm Goal: 2 ppm | Safe 2% of limit |
Total Trihalomethanes (TTHM) | 37.9 ppb Range: 16.4-64.7 Highest LRAA | 80 ppb | Safe 47% of limit |
Haloacetic Acids (HAA5) | 22.9 ppb Range: 7.7-37.2 Highest LRAA | 60 ppb | Safe 38% of limit |
Sulfate | 49.2 ppm Range: 22-69 | N/A | Safe |
Sodium | 23.35 ppm Range: 10.2-29.3 Highest average across treatment plants (Marston) | N/A | Safe |
PFOA | 0 ppt Range: 0-0 ND - UCMR5 - 0/15 samples detected | 4 ppt 0 | Safe |
PFOS | 0 ppt Range: 0-0 ND - UCMR5 - 0/15 samples detected | 4 ppt 0 | Safe |
MCL = Maximum Contaminant Level (EPA legal limit)
EPA Compliance History
Active Violations
Administrative issues pendingCurrent violations are administrative or monitoring-related. Water quality is not immediately affected, but stay informed about utility updates.
3-Year Violation Summary
6
Total Violations
0
Health-Related
6
Administrative
Health-Related Violations
Contaminant exceeded EPA maximum contaminant levels. The EPA recommends considering certified filtration.
Administrative Violations
Missed testing deadlines or reporting. Does not indicate water quality issues.
Who Provides Denver's Water?
Utility Name
DENVER WATER BOARD
EPA System ID (PWSID)
CO0116001
Primary Water Source
Surface Water
Population Served
1.3M
Frequently Asked Questions
Common questions about Denver tap water quality
Nearby Cities in Colorado
Aurora City of
Very Hard water
Colorado Springs
Hard water
Thornton City of
Very Hard water
Westminster City of
Very Hard water
Ft Collins City of
Soft water
Boulder City of
Soft water
This data is for informational purposes only. Water quality can vary by neighborhood and building. For official reports, contact your local water utility or the EPA. Learn about our methodology
Data source: Denver Water 2025 Water Quality Report (2024) • View report