Mondamin Water Supply, IA
Lead detected, under the action levels
Latest 90th-percentile lead: 2.57 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Mondamin Water Supply at a glance
Mondamin Water Supply serves about 339 people through 185 service connections, which makes it a very small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Harrison County, Iowa. EPA system ID: IA4349094; phone on file: 712-420-5313. They can tell you what your service line is made of and whether they pay to replace it.
Every lead result on file
That is down 1.23 ppb from 3.8 ppb in the period ending 2023. The highest 90th-percentile result EPA holds for Mondamin Water Supply is 4.9 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 2.57 ppb |
| 2023 | 3.8 ppb |
| 2020 | 2.6 ppb |
| 2017 | 4.9 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. Mondamin Water Supply's 2.57 ppb sits at the 72nd percentile in Iowa and the 78th nationally (higher means more lead).
Neighbouring systems
10 other systems share Harrison County; 7 of them have a higher latest lead result than Mondamin Water Supply. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Missouri Valley Water Supply | 2,678 | 2.9 ppb |
| Woodbine Water Department | 1,625 | 4 ppb |
| Logan Water Supply | 1,397 | 2 ppb |
| Dunlap Water Supply | 1,035 | 3 ppb |
| Modale Water Supply | 280 | 3 ppb |
| Pisgah Water Supply | 245 | 3.2 ppb |
| Sunnyside Village Mhp Llc | 190 | 0 (not detected) |
| Magnolia, City Of | 188 | 0 (not detected) |
| Little Sioux Water Department | 150 | 3 ppb |
| Valley View Water Association | 65 | 3.8 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Marshalltown, IA may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Mondamin 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. Why sampled homes are the worst-case ones is in the guide to reading the number. The action level is dropping - the 10 ppb rule from 2027.