Williams Bay Waterworks, WI
Above the federal action level
Latest 90th-percentile lead: 45 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. In the most recent monitoring period, more than 10% of the sampled homes measured above 15 ppb. Use a filter certified to NSF/ANSI 53 for lead for drinking and cooking now, and test your own tap.
About Williams Bay Waterworks
Williams Bay Waterworks serves about 2,601 people through 963 service connections, which makes it a small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Walworth County, Wisconsin. EPA system ID: WI2650060. Ask the utility on your bill for your address in their service line inventory.
Lead results over time
That is up 29 ppb from 16 ppb in the period ending 2025. The highest 90th-percentile result EPA holds for Williams Bay Waterworks is 45 ppb across 7 monitoring periods, 2 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 45 ppb over 15 |
| 2025 | 16 ppb over 15 |
| 2024 | 6.5 ppb |
| 2020 | 2.3 ppb |
| 2019 | 7.2 ppb |
| 2018 | 7.4 ppb |
| 2017 | 6 ppb |
Where this result ranks
Of the 947 Wisconsin systems with a lead result, the median latest reading is 1.33 ppb; 6 are over 15 ppb right now and 71 have gone over at some point. Williams Bay Waterworks's 45 ppb sits at the 100th percentile in Wisconsin and the 100th nationally (higher means more lead).
Other water systems in Walworth County
26 other systems share Walworth County; 0 of them have a higher latest lead result than Williams Bay Waterworks. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Whitewater Waterworks | 14,000 | 10 ppb |
| Elkhorn Waterworks | 10,317 | 13 ppb |
| Delavan Waterworks | 9,028 | 10 ppb |
| Lake Geneva Utility Commission | 7,107 | 8 ppb |
| East Troy Waterworks | 5,054 | 4.4 ppb |
| Bloomfield, Village Of | 4,071 | 1.95 ppb |
| Lake Como Sanitary Dist 1 | 3,038 | 2.5 ppb |
| Genoa City Waterworks | 2,766 | 4.56 ppb |
| Walworth Waterworks | 2,304 | 6.3 ppb |
| Geneva National Community Services | 2,250 | 0.71 ppb |
Your move
Use a filter certified to NSF/ANSI 53 for lead on the tap you drink and cook from, now, before you test. Then test your own tap. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Williams Bay Waterworks 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.