Onslow Water Supply, IA
Lead detected, under the action levels
Latest 90th-percentile lead: 0.6 ppb (monitoring period 2021-2023). 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.
Who runs the water here
Onslow Water Supply serves about 201 people through 110 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 Jones County, Iowa. EPA system ID: IA5358096; phone on file: 319-821-0124. They can tell you what your service line is made of and whether they pay to replace it.
Onslow Water Supply's lead record
Against the period ending 2020 (1.1 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Onslow Water Supply is 1.4 ppb across 3 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2023 | 0.6 ppb |
| 2020 | 1.1 ppb |
| 2017 | 1.4 ppb |
How Onslow Water Supply compares
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. Onslow Water Supply's 0.6 ppb sits at the 34th percentile in Iowa and the 45th nationally (higher means more lead).
Neighbouring systems
10 other systems share Jones County; 6 of them have a higher latest lead result than Onslow Water Supply. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Anamosa Municipal Water Supply | 4,457 | 1 ppb |
| Monticello Water Supply | 4,040 | 3 ppb |
| Anamosa State Penitentiary | 1,230 | 0 (not detected) |
| Olin Water Supply | 651 | 3.1 ppb |
| Wyoming Water System | 523 | 2.4 ppb |
| Oxford Junction Water Supply | 424 | 0.9 ppb |
| Martelle Water Works | 249 | 0 (not detected) |
| Center Junction (Eiruss) | 100 | 0 (not detected) |
| Morley Municipal Water Supply | 98 | 0 (not detected) |
| Bacon Addition | 81 | 2 ppb |
Your move
Test your own tap with a certified lab first-draw sample; Wyoming, 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 Onslow 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. Systems that went over once often dip back under; here is what that means.