Denver
CO

Is Denver, CO Tap Water Safe to Drink?

Denver, CO tap water has a qualified safety picture. The main concern is lithium, which was detected above EPA's non-regulatory health reference level of 10 µg/L in 33 of 34 ZIP codes in recent EPA testing. Several PFAS compounds were also detected, though all came in at or below their reporting thresholds. If you are pregnant or have an infant at home, a certified filter is worth considering.

4Water systems
34ZIP codes
97.1%ZIPs above EPA guideline
Metro areaDenver-Aurora-Centennial, CO
Latest data2025-10-06

Where Does Denver Get Its Water?

Denver, CO gets its drinking water primarily from surface water sources managed by Denver Water, the city's main public water utility. Denver Water operates one of the largest and most established water systems in the Rocky Mountain region, drawing from mountain snowmelt and reservoir storage in the South Platte and Colorado River basins.

The system is served by several major treatment plants. The Foothills Water Treatment Plant and the Marston Water Treatment Plant are two of the larger facilities. The Moffat Water Treatment Plant and the Northwater Water Treatment Plant also serve portions of the system.

A smaller utility, the City of Fort Lupton, also appears in this dataset and may serve customers in outlying areas of the Denver metro. Utilities with service area IDs from other states are not part of the Denver water system and are not discussed here.

How Is Denver Tap Water Treated?

Denver Water uses a multi-step treatment process that includes coagulation, filtration through membranes, and adsorption using powdered activated carbon. These steps work together to remove sediment, organic matter, and a range of chemical contaminants before water reaches your tap.

Disinfection is applied using both free chlorine and combined approaches to keep the water safe from bacteria and viruses throughout the distribution system. A residual disinfectant remains in the pipes so the water stays protected as it travels to your home.

The treatment train also includes additional polishing steps such as decarbonation and groundwater blending at certain points in the system, which helps manage mineral balance and taste. These are standard techniques for a large surface-water utility serving a major metro area.

What's in Denver Tap Water?

The main finding in recent EPA testing is lithium. The peak detected level was 10.4 µg/L, just above EPA's health reference level of 10 µg/L. Lithium was detected across all 34 ZIP codes in the dataset, and 33 of those 34 ZIPs had at least one sample above that 10 µg/L benchmark. It is important to understand that this benchmark is not an enforceable federal legal limit; no federal maximum contaminant level for lithium in drinking water currently exists.

Several PFAS compounds were also detected across Denver's water system, including PFTrDA, 6:2 FTS, PFBA, and HFPO-DA. All of these were detected at or at the reporting limit threshold, with maximum values at or below 0.007 µg/L. None of the PFAS detections exceeded any applicable EPA guideline based on this data.

Lithium in drinking water typically originates from natural geological sources, as it leaches from rocks and soils into surface water and groundwater. PFAS compounds can enter water supplies from a variety of upstream sources including industrial discharges and past use of firefighting foams, though the specific pathways for Denver's system are not detailed in this dataset.

ContaminantPeak detectedEPA guidelineZIPs detectedStatus
lithium 10.4 µg/L 10 µg/L 33 ZIPs Above guideline
PFTrDA 0.007 µg/L — 0 ZIPs Within guideline
6:2 FTS 0.005 µg/L — 0 ZIPs Within guideline
PFBA 0.005 µg/L — 0 ZIPs Within guideline
HFPO-DA 0.005 µg/L — 0 ZIPs Within guideline

Health Risk Profile for Denver

The health concern here centers on lithium. EPA has established a health reference level of 10 µg/L as a non-regulatory screening benchmark, meaning it is not an enforceable violation if water exceeds it, but it flags a level worth attention. Denver's peak detected lithium was 10.4 µg/L, modestly above that benchmark.

Pregnant individuals and infants are the groups EPA has focused on in its lithium health assessments, as developing brains may be more sensitive to lithium exposure. If you are pregnant, nursing, or preparing formula for an infant, reducing lithium intake from tap water is a reasonable precaution given the detection above the reference level.

For filtering lithium, a reverse osmosis system certified to NSF/ANSI 58 is the most effective option. NSF/ANSI is an independent third-party certification standard, so when you see that label on a filter product, it means the claim has been verified by outside testing. For the PFAS compounds detected in Denver's water, look for a filter also certified to NSF/ANSI 58 or NSF/ANSI P473, which specifically covers PFAS reduction.

The PFAS detections in this dataset are at very low levels, at or at the reporting threshold, and none exceeded applicable EPA guidelines. The science on low-level PFAS and lithium exposure is still developing, and EPA continues to review health evidence. A certified reverse osmosis filter addresses both concerns simultaneously and is the single best option for this water profile.

Best Broad-Spectrum Filters for This Water Profile

This city profile includes PFAS detections, chlorine disinfection, and other dissolved contaminants. Reverse osmosis (RO) systems certified under NSF/ANSI 58 provide broad reduction coverage; for PFAS specifically, confirm NSF/ANSI P473 or equivalent PFAS reduction certification.

Waterdrop G3P600 Reverse Osmosis System
Under-sink RO system

8-stage tankless RO system certified to NSF/ANSI 58, reduces 1,000+ contaminants including PFAS, lead, arsenic, fluoride, and nitrates.

See recommendations matched to your exact address: choose your ZIP code below.

Frequently Asked Questions about Denver Tap Water

Is Denver tap water safe to drink?

Denver tap water meets federal standards for PFAS compounds, but lithium was detected at 10.4 µg/L in recent EPA testing, just above the non-regulatory health reference level of 10 µg/L. That benchmark is not an enforceable legal limit, so this is not a compliance violation. Most healthy adults face low risk, but pregnant individuals and households with infants may want to use a certified filter as a precaution.

What contaminants are in Denver tap water?

Recent EPA testing found lithium at a peak of 10.4 µg/L, above EPA's non-enforceable health reference level of 10 µg/L. Several PFAS compounds were also detected, including PFTrDA at 0.007 µg/L, and 6:2 FTS, PFBA, and HFPO-DA each at 0.005 µg/L. All PFAS detections were at or below their reporting thresholds and did not exceed any EPA guideline in this dataset.

Where does Denver get its drinking water?

Denver Water, the city's primary utility, supplies tap water drawn from surface water sources in the South Platte and Colorado River basins, relying heavily on mountain snowmelt stored in reservoirs. Treatment is handled at several major plants including the Foothills, Marston, Moffat, and Northwater water treatment plants. The City of Fort Lupton also serves some customers in the broader metro area under a separate system.

Do I need a water filter in Denver?

A filter is not strictly required for healthy adults, but one is worth considering if you are pregnant or have an infant at home. Lithium was detected above EPA's health reference level, and several PFAS compounds were found at low levels. A reverse osmosis filter certified to NSF/ANSI 58 and NSF/ANSI P473 will address both concerns. NSF/ANSI certification means the filter's claims have been independently verified.

How often is Denver tap water tested?

Denver Water tests its water continuously under federal and state monitoring rules, and results are published annually in a Consumer Confidence Report. The data on this page comes from recent EPA sampling conducted through 2025, which included testing for emerging contaminants like PFAS and lithium across all parts of the Denver service area. The most recent samples in this dataset are dated October 2025.

What is the best water filter for Denver?

Given that Denver's water shows both PFAS detections and lithium above EPA's health reference level, the best choice is a reverse osmosis system certified to NSF/ANSI 58 and NSF/ANSI P473. Reverse osmosis is effective at reducing both PFAS compounds and lithium. If you are primarily concerned about chlorine taste or odor, a filter certified to NSF/ANSI 42 handles that separately, but it does not address PFAS or lithium.

Tap water reports by ZIP in Denver

Water utilities serving Denver, CO

Service area boundaries are approximate and based on state filings or modeled estimates. Contact your utility to confirm exact service at a specific address.

Modeled boundaries are shown with a dashed outline.

Also covers / overlaps with