Wisconsin Septic & Well Water Rules

Wisconsin's Department of Safety and Professional Services (DSPS) regulates private onsite wastewater treatment systems (POWTS), and counties run maintenance tracking programs.

This is a short state page. It covers only the facts we've verified from official sources so far.

Official lookups

Required maintenance

Counties must run a POWTS maintenance program that tracks inspections and sends due-date notices.
Under SPS 383.55, systems must be visually inspected or serviced at least every three years, or up to five years for occasionally occupied buildings if the county allows. The tank must be pumped when sludge and scum reach one-third of its volume.
Maintenance must be reported to the county within 30 days.

Private well testing

Wisconsin DNR recommends testing for bacteria (total coliform and E. coli) and nitrate at least once a year, and right away if the water's taste, color or smell changes. Use a Wisconsin-certified lab, such as the Wisconsin State Laboratory of Hygiene.

Frequently asked questions

How often must a septic system be inspected in Wisconsin?

At least every three years under the county maintenance program (SPS 383.55), with pumping when solids reach one-third of tank volume.

Sources

Last checked: October 21, 2026