Water system

Williams Bay Waterworks

Name: Williams Bay Waterworks drinking water quality
Creator: TapWaterZip
License: https://www.usa.gov/government-works

Wisconsin EPA ID WI2650060 2,601 people Groundwater

What this means for you

Is it safe to drink right now?: The system’s latest lead 90th-percentile result is above today’s 15 ppb action level. That does not mean every home is over the limit — lead often comes from plumbing in the building — but it is a red flag. Flush cold water before drinking and consider a certified lead filter until you can test your own tap.
Should I use a filter?: Yes, we recommend considering one. Lead results are high enough that a certified lead-reduction filter is a sensible precaution.
What kind of filter?: For lead, choose NSF/ANSI 53 certified for lead reduction (or RO under 58). See matched standards and product picks.

This is general information from public EPA data, not medical advice. Lead often comes from a home’s own pipes, so only a test of your tap can tell your exposure. If you are pregnant, caring for an infant, or have a weakened immune system, ask your doctor or health department.

Summary: 1 health-based violation in the last 5 years; 10 monitoring/reporting violations; 5 not yet resolved; No UCMR 5 PFAS results on file; Lead 90th percentile ABOVE the action level (2026).

EPA data snapshot 2026Q3. Grade is TapWaterZip's own score — see methods.

PFAS (“forever chemicals”), EPA UCMR 5

No UCMR 5 results on file (mostly smaller systems weren’t required to test).

Lead and copper

Lead 90th percentile45 ppb2026-06-30

Current action level15 ppbLCRI lowers to 10 ppb on Nov 1, 2027

Above today’s 15 ppb lead action level. Ask your utility about corrosion control and test water at your tap.

Violations (last 5 years)

Began	Type	Contaminant / rule	Status
2026-01-01	Missed or late testing/reporting	Lead and Copper Rule	Archived
2026-01-01	Missed or late testing/reporting	Lead and Copper Rule	Archived
2026-01-01	Missed or late testing/reporting	Lead and Copper Rule	Unaddressed
2025-09-11	Other paperwork/notice violation	Public Notice	Resolved
2025-07-01	Required treatment not done	Lead and Copper Rule	Resolved
2025-07-01	Other paperwork/notice violation	Public Notice	Unaddressed
2025-07-01	Other paperwork/notice violation	Public Notice	Unaddressed
2025-07-01	Other paperwork/notice violation	Public Notice	Unaddressed
2025-01-01	Missed or late testing/reporting	Lead and Copper Rule	Unaddressed
2025-01-01	Missed or late testing/reporting	Lead and Copper Rule	Archived
2025-01-01	Missed or late testing/reporting	Lead and Copper Rule	Archived

Filters matched to this water

FILTER PICKS

Look for filters certified (NSF, IAPMO or WQA) to these standards for the specific contaminant. Buttons open the maker’s page or an Amazon search; use “Check NSF listing” to verify a model’s claims. No affiliate links yet — grades are never sold.