Granville Water Supply, IA
Lead detected, under the action levels
Latest 90th-percentile lead: 1.4 ppb (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. 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
Granville Water Supply serves about 310 people through 186 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 surface water, in Sioux County, Iowa. EPA system ID: IA8429002; phone on file: 712-727-3365. They can tell you what your service line is made of and whether they pay to replace it.
Every lead result on file
Against the period ending 2022 (1 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Granville Water Supply is 4.2 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 1.4 ppb |
| 2022 | 1 ppb |
| 2019 | 4.2 ppb |
| 2016 | 1.2 ppb |
How Granville 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. Granville Water Supply's 1.4 ppb sits at the 50th percentile in Iowa and the 62nd nationally (higher means more lead).
Neighbouring systems
14 other systems share Sioux County; 9 of them have a higher latest lead result than Granville Water Supply. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Sioux Center Municipal Water Department | 8,231 | 4.4 ppb |
| Orange City Municipal Water Department | 6,267 | 0 (not detected) |
| Southern Sioux County Rural Water | 5,420 | 2.1 ppb |
| Rock Valley Water Supply | 4,059 | 2 ppb |
| Rural Water System #1 | 3,428 | 1.2 ppb |
| Hawarden Water Supply | 2,700 | 0 (not detected) |
| Hull Water Supply | 2,384 | 1.8 ppb |
| Rock Valley Rural Water District | 2,250 | 2.4 ppb |
| Alton Municipal Water Department | 1,248 | 0.87 ppb |
| Hospers Municipal Water Dept | 718 | 6.1 ppb |
Your move
Test your own tap with a certified lab first-draw sample; Granville, 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 Granville 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.