Wisconsin Septic (POWTS): what it allows on a lot
Septic (POWTS) is Wisconsin law, and the official source is at dsps.wi.gov.
Private onsite wastewater systems need a county sanitary permit and soil test.
Whether it applies to one lot turns on where the lot is and what it is zoned; the city, county or state office named in the law decides. Mapped areas are approximate. This is a plain reading of public law with its source, not legal advice.
Free, no account. ParcelSheet shows the lot's mapped size, parcel lines and flood zone, and this law on the lot's Wisconsin sheet.
Other Wisconsin laws on a lot: Shoreland zoning (NR 115).