Sioux City Water Supply, IA
Lead detected, under the action levels
Latest 90th-percentile lead: 2 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.
About Sioux City Water Supply
Sioux City Water Supply serves about 85,791 people through 29,424 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 Woodbury County, Iowa. EPA system ID: IA9778054; phone on file: 712-279-6150. Call that number and ask whether your address has a lead, galvanized or unknown service line.
Sioux City Water Supply's lead record
Against the period ending 2022 (3 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Sioux City Water Supply is 5 ppb across 6 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 2 ppb |
| 2022 | 3 ppb |
| 2019 | 2 ppb |
| 2018 | 2 ppb |
| 2017 | 5 ppb |
| 2016 | 2 ppb |
How Sioux City 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. Sioux City Water Supply's 2 ppb sits at the 67th percentile in Iowa and the 73rd nationally (higher means more lead).
Nearby utilities
16 other systems share Woodbury County; 5 of them have a higher latest lead result than Sioux City Water Supply. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Sergeant Bluff Water Supply | 5,015 | 4 ppb |
| Moville Water Supply | 1,687 | 0.82 ppb |
| Sloan Water Supply | 1,042 | 0.93 ppb |
| Lawton Water Supply | 988 | 4.3 ppb |
| Correctionville Water Supply | 766 | 0.8 ppb |
| Anthon Municipal Water System | 545 | 1.8 ppb |
| Pierson Water Supply | 345 | 0.8 ppb |
| Danbury Water Supply | 320 | 1.2 ppb |
| Salix Water Supply | 295 | 0.6 ppb |
| Bronson Water Supply | 294 | 1.9 ppb |
What to do in your house
Test your own tap with a certified lab first-draw sample; Sioux City, 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 Sioux City 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. What a 90th-percentile result does and does not tell you: how to read a lead result. Size matters more than most people expect: small vs large water systems.