Several standards and building codes within the state of Wisconsin covers water heaters. Heaters coming into contact with potable water supplies must adhere to ANSI standards Z21.10.1 or Z1.10.3. All water heaters installed in Wisconsin remain subject to the Wisconsin Plumbing Code.
The Wisconsin Plumbing Code requires installation by a qualified plumber for water heaters using potable water. Also, landlords installing water heaters in buildings must not set them to heat water beyond 125 degrees Fahrenheit.
Efficiency standards set by the U.S. government exceed the standards introduced by the state and municipalities, meaning Wisconsin must adhere to federal energy efficiency standards. As of 2011, no legislation exists in Wisconsin to enforce federal energy efficiency standards, however.