Tap Water Results

Is Longmont, CO tap water safe?

Data: U.S. EPA · How we read the data · How we check it

Summary

No federal limits exceeded in EPA data for City of Longmont.

4 public water systems serve parts of Longmont. The largest, City of Longmont, serves 104,178 people. Your water bill names your system.

Largest system

City of Longmont

104,178 people · Surface water · EPA ID CO0107485

Buys treated water from Left Hand Water District.

PFASHighest averageLimitStatus
PFOA
Not detected
–4 pptNot detected
PFOS
Not detected
–4 pptNot detected
PFHxS
Not detected
–10 pptNot detected
PFNA
Not detected
–10 pptNot detected
HFPO-DA (GenX)
Not detected
–10 pptNot detected

ppt = parts per trillion. "Highest average" is the highest average at any of the system's entry points, the way EPA compares results with the limits.

Lead: 1.6 ppb at the 90th percentile (Dec 2025, and 9 in 10 homes sampled were at or below it) Below action level
Health-based violations since 2016: 0

Full City of Longmont results

Across Colorado, 4 of 158 water systems EPA tested had PFAS above a 2024 federal limit, and 2 systems were above the lead action level in results from the last five years. Colorado results.

Longmont homes and lead pipes

37%
of homes built before 1980 (Colorado 40%, US 50%)
6%
built before 1950 (Colorado 9%)
38%
of households rent (Colorado 34%)

Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. Renting? Ask your landlord what the service line is made of, because it's their pipe to replace. How to check your own line.

Housing: Census American Community Survey 2020–2024 5-year estimates for Longmont city (tables B25034, B25003). Estimates for small places have a margin of error.

Other water systems serving Longmont

  • Left Hand Water District
    20,280 people · Surface water · Colorado · reported ZIPs here
    No PFAS above limits
  • Countryside of Longmont Water System
    775 people · Purchased surface water · Colorado · lists this city
    Not in EPA's PFAS sample
  • St Vrain MHP LLC
    544 people · Purchased surface water · Colorado · lists this city
    Not in EPA's PFAS sample

How nearby cities compare

CityMain water systemPFASLead (90th pct.)
Erie 9 mi
Town of Erie
Town of ErieNone above limits2.6 ppb
Lafayette 12 mi
City of Lafayette
City of LafayetteNone above limits2 ppb
Boulder 13 mi
City of Boulder
City of BoulderNone above limits2 ppb
Broomfield 15 mi
County of Broomfield City and
County of Broomfield City andNone above limits2.5 ppb
Loveland 17 mi
City of Loveland
City of LovelandNone above limits3.3 ppb
Northglenn 19 mi
City of Northglenn
City of NorthglennNone above limits1.7 ppb
Longmont ZIP codes (1)
  • 80501

Questions

Is Longmont tap water safe to drink?

City of Longmont has had no health-based violations since 2016. Utility data can't show lead from your own pipes: if your home was built before 1986, test your tap. Your utility's annual Consumer Confidence Report is the official summary.

Who supplies water in Longmont, CO?

4 public water systems serve parts of Longmont. The largest is City of Longmont (104,178 people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.

Does Longmont tap water have PFAS?

None detected above EPA's reporting limits. City of Longmont had no PFAS detected in EPA's 2023–2025 testing. "Not detected" means below the reporting limit (about 2 to 20 ppt), not proven zero.

Do Longmont homes have lead pipes?

Census estimates put 37% of Longmont homes as built before 1980 (Colorado: 40%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. City of Longmont's service line inventory says what your line is made of. The only way to know for your home is to check the line where it enters the house and test your tap.

Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.