Minnesota Plumbing Code

The Minnesota Plumbing Code is Minn. Rules chapter 4714, published as the 2020 Minnesota Plumbing Code. It incorporates the 2018 Uniform Plumbing Code (UPC), published by IAPMO, by reference, with Minnesota amendments. It took effect Dec. 17, 2021. It replaced the 2015 Minnesota Plumbing Code, which was based on the 2012 UPC.

The Minnesota Plumbing Board adopts the plumbing code by rule (Minn. Stat. 326B.435), and the Department of Labor and Industry (DLI) administers it. Under Minn. Stat. 326B.43, the plumbing code's minimum standards are uniform and apply to all new plumbing installations performed anywhere in the state, including additions, extensions, alterations, and replacements. Part 4714.0101 repeats that scope. Unlike the building code, the plumbing code does not depend on a city choosing to adopt it.

Minnesota amends the UPC much more than it amends the NEC. The amendments are written as parts of chapter 4714, and the part numbers generally track the UPC section they change (for example, part 4714.0712 goes with UPC section 712). IAPMO publishes the 2020 Minnesota Plumbing Code as a single book with the amendments merged in, so a section number in that book matches the 2018 UPC number while its text may be Minnesota's. DLI's summary of the rulemaking says chapter 4714 incorporates UPC chapters 2 to 11, 16, and 17 and Appendices A, B, and I. UPC chapter 1 (administration) is not on that list. Administrative rules for plumbing come from chapter 4714 and from the State Building Code administration rules in Minn. Rules chapter 1300, such as part 1300.0215 on plumbing inspections.

Drills on this site cite 2018 UPC section numbers. Each answer's Minnesota note says whether a Minnesota amendment to that section is known. When the note says none is known, check chapter 4714 before relying on the model-code text.

Next edition: a Plumbing Board ad hoc rulemaking committee has been reviewing the 2024 UPC chapter by chapter since late 2023 (its minutes are posted on dli.mn.gov). This page could not confirm a proposed or effective date for a new Minnesota Plumbing Code, so check DLI's plumbing code page.

Plumbing in Minnesota is licensed work under Minn. Stat. 326B.42 to 326B.49. No individual may engage in or work at the business of a master plumber, restricted master plumber, journeyworker plumber, or restricted journeyworker plumber without a license from DLI (Minn. Stat. 326B.46). A master plumber may also work as a journeyworker, restricted journeyworker, or restricted master. A journeyworker may also work as a restricted journeyworker.

A business that plans, superintends, or installs plumbing, or installs plumbing as part of selling plumbing materials, must at all times have a licensed master plumber in charge of its plumbing work and responsible for proper installation. In cities and towns with a population of fewer than 5,000 (last federal census), a restricted master plumber can fill that role (326B.46, subd. 1(b)). Except as subdivision 1a allows, no person may perform or offer to perform plumbing work, with or without compensation, without a contractor's license (subd. 1(c)). Subdivision 1a covers, for example, an owner working on their own residence and a licensed plumber working for an employer that holds the contractor license. Anyone contracting to do plumbing work must also give a bond to the state of at least $25,000 and carry liability insurance (subd. 2). A handyman or remodeler without a plumbing contractor license therefore cannot do plumbing work for customers.

People who are not licensed may do plumbing work only as a registered plumber's apprentice or registered unlicensed individual, under the direct supervision of a licensed master, restricted master, journeyworker, or restricted journeyworker plumber employed by the same employer (Minn. Stat. 326B.47). Direct supervision means the licensed plumber is at the job location, immediately available, and reviews the work before it is operated. Apprentices and registered unlicensed individuals may not supervise plumbing work or assign it to other unlicensed people.

Homeowners have a narrow exemption. Anyone not licensed may do plumbing work that meets the Plumbing Board's standards on premises, or that part of premises, owned and actually occupied by the worker as a residence, unless a local ordinance forbids it (Minn. Stat. 326B.46, subd. 1(a); subd. 1a(a) says such a person also needs no contractor license). The person doing the work must be the owner-occupant, so the exemption does not extend to anyone the owner hires. It also follows the words 'that part of premises': in a duplex where the owner lives in one unit, it covers only the owner's own unit. Metro city permit handouts (for example Anoka's and White Bear Lake's) state that it is illegal for an unlicensed owner to do plumbing on property that is rented, leased, or occupied by others, and that a licensed plumbing contractor must take out the permits for non-owner-occupied units. The exemption covers the license, not the permit or the inspections.

Where the State Building Code is enforced, Minn. Rules 1300.0120, subp. 1 requires an owner or authorized agent to apply to the building official and get a permit before installing, altering, repairing, or replacing a plumbing system, or before having that work done. For a house in such a city, the local building department issues the plumbing permit and does the inspections. Many cities issue plumbing permits only to licensed and bonded plumbing contractors, or to an owner-occupant doing their own work. Check with the city before assuming who can pull the permit. Minn. Rules 1300.0215 also lets the administrative authority waive the permit, inspection, and test for a short list of minor work in one- and two-family dwellings when it creates no unsanitary or hazardous condition. The list covers reconnecting an existing water line to a replacement appliance, replacing the internal parts of toilets, faucets, or valves, replacing a sink faucet, and replacing or resetting a toilet, each only when the piping is not altered.

Plumbing plan review is a separate state step. Minn. Rules 1300.0215, subp. 6 requires plans and specifications to be submitted and approved before installation for a plumbing system that serves the public, serves a considerable number of people, or could affect public health in any manner. The rule says review is not required for single-family dwellings. DLI describes the review as covering new work, additions, extensions, and alterations in public and commercial buildings and in residential buildings of five or more units. DLI does that review unless the city has a plan review agreement with the state (Minn. Stat. 326B.43, subd. 2) or is a city of the first class (Minneapolis, St. Paul, Duluth, Rochester). A city with an agreement also agrees to do the plumbing-code inspections for the projects it reviews. DLI says state projects, such as health care facilities licensed by the Minnesota Department of Health and state-owned buildings, still come to DLI.

Rough-in comes before cover. Minn. Rules 1300.0215 says no building drainage or plumbing system, or part of one, may be covered until it has been inspected, tested, and approved. Plumbing covered before that must be uncovered when the administrative authority directs. New plumbing, and existing plumbing that has been altered, extended, or repaired, must be tested and approved by the administrative authority before it is put into use, and the administrative authority performs the final inspection and witnesses the test. The tests themselves come from the plumbing code. The model UPC (section 712.1) allows water or air on drain, waste, and vent piping but bars air tests on plastic pipe. Minnesota's amendment in part 4714.0712 allows air tests on plastic pipe, according to the Plumbing Board's rulemaking statement, because water tests are unsafe in winter.

Who inspects depends on the job and the place. In a city that enforces the State Building Code, the city issues plumbing permits and inspects, including for houses. For plumbing that needs state plan review, DLI says its plan review program also inspects the work wherever there is no plan review agreement. In areas that have not adopted the State Building Code, DLI is the administrative authority and inspects new plumbing in public, commercial, industrial, and state-licensed buildings. The plumbing code itself applies everywhere (Minn. Stat. 326B.43), but for a house in an area with no local building department there may be no local plumbing permit, so ask DLI what applies.