Sioux Rural Water System, SD
Lead detected, under the action levels
Latest 90th-percentile lead: 4 ppb (monitoring period 2025-2025). 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
Sioux Rural Water System serves about 4,280 people through 1,712 service connections, which makes it a medium-sized system under EPA's size classes. It is privately owned and draws groundwater, in Clark,Codington,Deuel,Hamlin County, South Dakota. EPA system ID: SD4600866; phone on file: 6058821321. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Sioux Rural Water System'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 Rural Water System is 5 ppb across 4 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 4 ppb |
| 2022 | 3 ppb |
| 2019 | 5 ppb |
| 2016 | 5 ppb |
Against other South Dakota systems
Of the 458 South Dakota systems with a lead result, the median latest reading is 2 ppb; 0 are over 15 ppb right now and 6 have gone over at some point. Sioux Rural Water System's 4 ppb sits at the 88th percentile in South Dakota and the 88th nationally (higher means more lead).
What to do in your house
Test your own tap with a certified lab first-draw sample; Watertown, SD 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 Rural Water System 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.