Licensing and permits
Plumbers in Wisconsin are licensed by the Department of Safety and Professional Services, and its online credential search shows whether a license is active. Cities and villages issue their own permits for replacing a heater; in Milwaukee that office is the Department of Neighborhood Services.
Cold water and hard wells
Lake Michigan cities such as Milwaukee, Racine and Kenosha see winter inlet water in the 30s, which makes sizing the main concern. Madison and much of the interior rely on deep wells that are considerably harder, so sediment and scale matter more there. Wisconsin repairs usually cost $150 to $600, and a gas tank replacement in a basement generally falls between $1,400 and $2,900; see water heater replacement.