- EPA's UCMR 5 testing looked for 30 contaminants here and found 1.
- Lithium: found in 8 of 8 samples, average 22 µg/L, highest 33 µg/L (EPA UCMR 5 testing, Jan 2025–Oct 2025)
- Lead: 9 in 10 homes tested came in at or below 0 ppb, at or below EPA's 15 ppb action level (latest EPA result for a testing period that ran on or after July 1, 2021: Jan 1, 2023–Dec 31, 2025). This is one number for the whole water system, from homes the utility tested. It isn't a result for your home.
Public EPA test results
Can you drink Johnston tap water? What EPA records show
EPA system ID IA7740011 · serves Johnston, IA · about 24,897 people (EPA records)
Here's what EPA has on file for this water system: its testing for newer contaminants like PFAS (UCMR 5), lead testing and violations. It's not a test of your tap, and there's no Water Score here.
Public EPA test results
Johnston Municipal Water Supply (EPA IA7740011)
EPA data as of October 14, 2026. For Johnston's main utility, Johnston Municipal Water Supply: We found no health-standard violations in EPA's records for this system (IA7740011) since July 1, 2021, as of October 14, 2026. PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
What EPA records show for Johnston Municipal Water Supply, as of October 14, 2026
We found no health-standard violations in EPA's records for this system (IA7740011) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Johnston Municipal Water Supply (SDWIS). Data as of October 14, 2026.
Lead: 9 in 10 homes tested came in at or below 0 ppb, at or below EPA's 15 ppb action level (latest EPA result for a testing period that ran on or after July 1, 2021: Jan 1, 2023–Dec 31, 2025). This is one number for the whole water system, from homes the utility tested. It isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found 1.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does Johnston Municipal Water Supply use chloramine?
We didn't find chloramine in Johnston Municipal Water Supply's EPA treatment records. That's not a complete list; your utility's annual water quality report says which disinfectant it uses.