Arapahoe County tap water: hardness, PFAS and lead
Arapahoe County, Colorado has about 666,918 residents (Census 2024 estimate) and 30 community water systems in EPA records. The largest local system is Aurora City of, serving about 533,407 people from surface water.
✓ 0 of 6 largest systems with health-based violationsPFAS detected at 4 of 4 sampled systemsHardness 6.6 gpg (high confidence)
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.
How hard is Arapahoe County water?
Aurora City ofMeasured (utility report, 2025) · High confidence
6.6 gpg(113 mg/L), moderately hard · range 56–154 mg/L
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.
Softener size at 6.6 gpg
For a 3-person home using 57 gallons per person per day and regenerating weekly, you'd remove about 7,900 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 6 biggest of 30 community water systems on EPA records for this county. Service areas don't follow county lines; your water bill names your provider.
Aurora City of
CO0103005 · serves about 533,407 people · Surface water
✓ No health-based violations✓ Lead below action levelPFAS detected (4 types)
Lead 90th percentile: 4.7 ppb (period starting 2026-01-01). Action level: 15 ppb (drops to 10 ppb on Nov 1, 2027).
PFBA: highest sample 7.8 ppt (1 of 12 samples); no federal limit
PFPeA: highest sample 7.2 ppt (1 of 12 samples); no federal limit
PFHxA: highest sample 5.6 ppt (1 of 12 samples); no federal limit
PFBS: highest sample 3.3 ppt (1 of 12 samples); no individual limit; counted in EPA's PFAS mixture (hazard index) limit
CO0103035 · serves about 66,130 people · Surface water
✓ No health-based violations✓ Lead below detectionPFAS detected (2 types)
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).
PFBA: highest sample 6.2 ppt (1 of 10 samples); no federal limit
PFPeA: highest sample 4.7 ppt (2 of 10 samples); no federal limit
CO0203002 · serves about 31,000 people · Groundwater
✓ No health-based violations✓ Lead below detectionPFAS detected (5 types)
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).
PFPeA: highest sample 7.9 ppt (2 of 14 samples); no federal limit
PFHxA: highest sample 6.8 ppt (2 of 14 samples); no federal limit
PFBS: highest sample 6.1 ppt (2 of 14 samples); no individual limit; counted in EPA's PFAS mixture (hazard index) limit
PFBA: highest sample 5.5 ppt (1 of 14 samples); no federal limit
PFOA: highest sample 4.6 ppt (1 of 14 samples); federal limit 4.0 ppt as a running annual average
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.
Test your own tap
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.
Common questions about Arapahoe County water
Is tap water in Arapahoe County safe to drink?
None of the 6 largest systems here have a health-based violation in EPA records since October 2021. Aurora City of's most recent lead 90th percentile was 4.7 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.
How hard is the water in Arapahoe County?
Aurora City of reports about 6.6 grains per gallon (113 mg/L), which is moderately hard. For a 3-person home at 6.6 gpg, our softener calculator suggests a 24,000 grain unit as a starting point.
Is there PFAS in Arapahoe County water?
4 of the 4 sampled systems listed here detected at least one PFAS in EPA's UCMR 5 testing, and one result was above the level of a federal limit in at least one sample. A detection isn't a violation: federal PFAS limits apply to running annual averages starting in 2029.
Which water system serves my address in Arapahoe County?
Most homes are served by Aurora City of 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.