Johnston Municipal Water Supply, IA
Lead reported as not detected
Latest 90th-percentile lead: reported as 0 (not detected) (monitoring period 2023-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest 90th-percentile result was reported as 0 (not detected at the lab's limit). That says the sampled homes were low, not that your home has no lead service line. Check your utility's service line inventory for your address.
About Johnston Municipal Water Supply
Johnston Municipal Water Supply serves about 24,897 people through 7,657 service connections, which makes it a large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Polk County, Iowa. EPA system ID: IA7740011; phone on file: 515-278-0822. They can tell you what your service line is made of and whether they pay to replace it.
Johnston Municipal Water Supply's lead record
Against the period ending 2022 (0 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Johnston Municipal Water Supply is 1.6 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 0 (not detected) |
| 2022 | 0 (not detected) |
| 2019 | 1.6 ppb |
| 2018 | 1.5 ppb |
Where this result ranks
Of the 1,066 Iowa systems with a lead result, the median latest reading is 1.4 ppb; 4 are over 15 ppb right now and 36 have gone over at some point. Johnston Municipal Water Supply's reported as 0 (not detected) sits at the 31st percentile in Iowa and the 39th nationally (higher means more lead). Systems reporting 0 tie at the bottom, so the rank mostly reflects size among them.
Nearby utilities
34 other systems share Polk County; 9 of them have a higher latest lead result than Johnston Municipal Water Supply. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Des Moines Water Works | 246,055 | 0 (not detected) |
| Ankeny, City Of | 76,207 | 0 (not detected) |
| Urbandale Water Utility | 45,605 | 0 (not detected) |
| Altoona Water Supply | 22,436 | 5.6 ppb |
| Clive Water Department | 20,277 | 0 (not detected) |
| Grimes Water Supply | 17,997 | 0 (not detected) |
| Bondurant Muni Water Supply | 9,393 | 1.3 ppb |
| Southeast Polk Rwd | 7,565 | 0 (not detected) |
| Polk City Water Supply | 6,533 | 1.3 ppb |
| Mitchellville Water Supply | 2,515 | 0 (not detected) |
What to do in your house
Look up your address in Johnston Municipal Water Supply's service line inventory. If it says lead, galvanized or unknown, test your tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Johnston Municipal Water Supply whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. The lead result guide covers how utilities pick the homes they sample. A zero today does not rule out a jump later - the rules are tightening in 2027.