Tap Water Results

Is Johnston, IA 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 Johnston Municipal Water Supply.

2 public water systems serve parts of Johnston. The largest, Johnston Municipal Water Supply, serves 24,897 people. Your water bill names your system.

Largest system

Johnston Municipal Water Supply

24,897 people · Purchased surface water · EPA ID IA7740011

Buys treated water from Ciww (DMWW), Des Moines Water Works.

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: 0 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

Across Iowa, 1 of 151 water systems EPA tested had PFAS above a 2024 federal limit, and 4 systems were above the lead action level in results from the last five years. Iowa results.

Johnston homes and lead pipes

7%
of homes built before 1980 (Iowa 62%, US 50%)
1%
built before 1950 (Iowa 28%)
29%
of households rent (Iowa 28%)

Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. How to check your own line.

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

Other water systems serving Johnston

  • Camp Dodge Water Supply
    1,169 people · Groundwater · Iowa · lists this city
    Not in EPA's PFAS sample

How nearby cities compare

CityMain water systemPFASLead (90th pct.)
Urbandale 5 mi
Urbandale Water Utility
Urbandale Water UtilityNone above limits0 ppb
Ankeny 7 mi
City of Ankeny
City of AnkenyNone above limits0 ppb
Des Moines 10 mi
Des Moines Water Works
Des Moines Water WorksNone above limits0 ppb
West Des Moines 10 mi
West Des Moines Water Works
West Des Moines Water WorksNone above limits0 ppb
Waukee 11 mi
Waukee Water Supply
Waukee Water SupplyNone above limits0 ppb
Ames 24 mi
Ames Water Treatment Plant
Ames Water Treatment PlantNone above limits0 ppb
Johnston ZIP codes (1)
  • 50131

Questions

Is Johnston tap water safe to drink?

Johnston Municipal Water Supply 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 Johnston, IA?

2 public water systems serve parts of Johnston. The largest is Johnston Municipal Water Supply (24,897 people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.

Does Johnston tap water have PFAS?

None detected above EPA's reporting limits. Johnston Municipal Water Supply 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 Johnston homes have lead pipes?

Census estimates put 7% of Johnston homes as built before 1980 (Iowa: 62%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. Johnston Municipal Water Supply'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.