Wis. Stat. § 704.06: Water heater thermostat settings.

A landlord of premises which are subject to a residential tenancy and served by a water heater serving only that premises shall set the thermostat of that water heater at no higher than 125 degrees Fahrenheit before any new tenant occupies that premises or at the minimum setting of that water heater if the minimum setting is higher than 125 degrees Fahrenheit.