Denver County, Colorado has about 729,019 residents (Census 2024 estimate) and 5 community water systems in EPA records. The largest local system is Denver Water Board, serving about 1,287,000 people from surface water.
Public-record figures, not a test of your tap. Not 100% accurate or guaranteed. Confirm with a water test, your utility or a qualified pro before you buy or act.
Denver Water Board Measured (utility report, 2025 (data year; published as 2026 report)) · High confidence
6.1 gpg (105 mg/L), moderately hard · range 55–124 mg/L
Source: DENVER WATER BOARD water quality report, 2025 (data year; published as 2026 report)
Public-record figures, not a test of your tap. Not 100% accurate or guaranteed. Confirm with a water test, your utility or a qualified pro before you buy or act.
For a 3-person home using 57 gallons per person per day and regenerating weekly, you'd remove about 7,302 grains between regenerations. Suggested size: 24,000 grain.
Estimate only. Not 100% accurate or guaranteed. Confirm with a water test, your utility or a qualified pro before you buy or act.
The 5 biggest of 5 community water systems on EPA records for this county. Service areas don't follow county lines; your water bill names your provider.
CO0116001 · serves about 1,287,000 people · Surface water
Lead 90th percentile: 3.6 ppb (period starting 2026-01-01). Action level: 15 ppb (drops to 10 ppb on Nov 1, 2027).
CO0116175 · serves about 22,000 people · Surface water
Lead 90th percentile: 9 ppb (period starting 2002-01-01) Older result. Action level: 15 ppb (drops to 10 ppb on Nov 1, 2027).
CO0116104 · serves about 3,447 people · Surface water
Lead 90th percentile: <DL (below the lab detection/reporting limit; reported as 0) (period starting 2025-01-01). Action level: 15 ppb (drops to 10 ppb on Nov 1, 2027).
CO0116122 · serves about 200 people · Surface water
Lead 90th percentile: <DL (below the lab detection/reporting limit; reported as 0) (period starting 2025-07-01). Action level: 15 ppb (drops to 10 ppb on Nov 1, 2027).
CO0116484 · serves about 147 people · Surface water
Lead 90th percentile: <DL (below the lab detection/reporting limit; reported as 0) (period starting 2026-01-01). Action level: 15 ppb (drops to 10 ppb on Nov 1, 2027).
Public-record figures, not a test of your tap. Not 100% accurate or guaranteed. Confirm with a water test, your utility or a qualified pro before you buy or act.
A PFAS detection is not a violation. Federal limits (4 ppt for PFOA and PFOS) apply to running annual averages, with compliance required by 2029. In May 2026 EPA proposed extending the PFOA/PFOS deadline to 2031 and removing other PFAS limits; not final as of 2026-10-21.
These are public records for whole systems. Your home's pipes, fixtures and any private well can change what you drink. A certified lab test or a hardness test strip gives you your own numbers. Then use our PFAS and lead filter selector to see which certifications to look for.
2 of the 5 largest systems here have at least one health-based violation in EPA records since October 2021 (see each system below for status). Denver Water Board's most recent lead 90th percentile was 3.6 ppb (2026), below the 15 ppb action level. Public records can't guarantee what comes out of your tap, especially with older plumbing, so a home test is the surest check.
Denver Water Board reports about 6.1 grains per gallon (105 mg/L), which is moderately hard. For a 3-person home at 6.1 gpg, our softener calculator suggests a 24,000 grain unit as a starting point.
None of the 2 sampled systems listed here detected PFAS above EPA's reporting levels in UCMR 5 testing.
Most homes are served by Denver Water Board or one of the other systems listed on this page, but service areas don't follow county lines. Your water bill names your provider, and its annual Consumer Confidence Report has the full test results.
Data as of October 21, 2026. Figures are copied from public records and combined with our own calculations; they can be out of date or wrong. Tapped Out isn't affiliated with any utility or the EPA. Written and reviewed by the Tapped Out team. How we calculate · All sources.