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Minnesota Department of Labor and Industry

Manufactured home on-site plumbing testing

Manufactured Structures Bulletin 36


Manufacturers, Manufactured home Dealers, Installers & Building Officials


Scott McLellan, Assistant Director Construction Codes & Licensing Division


May 2007


Manufactured Home on-site Plumbing Testing


The Minnesota Construction Codes and Licensing Division has learned that on-site testing of drain/waste lines on manufactured homes is not being conducted in a uniform manor in Minnesota. Bulletin #36 is intended to help clarify the manner in which the drain/waste lines are to be tested when the home is installed at the site of occupancy.

When the manufactured home is constructed at the manufacturing facility, its drainage system is required to be tested in accordance with the HUD Code of Federal Regulations (CFR) 3280.612 (b). CFR 3280.612 (b) requires the drainage system to be tested at the production facility by one of three methods.



Water test. Before plumbing fixtures are connected, all of the openings into the piping shall be plugged and the entire piping system subjected to a static water test for 15 minutes by filing it with water to the top of the highest vent opening.



Air test. After all fixtures have been installed, the traps filled with water, and the remaining openings securely plugged, the entire system shall be subjected to a 2-inch (manometer) water column air pressure.



Flood level test. The manufactured home shall be in a level position, all fixtures shall be connected, and the entire system shall be filled with water to the rim of the water closet bowl (tub and shower drains shall be plugged). After all trapped air has been released, the test shall be sustained for not less than 15 minutes without evidence of leaks. The system shall be unplugged and emptied. The waste piping above the level of the water closet shall then be tested and show no indication of leakage when the high fixtures are filled with water and empty simultaneously to obtain maximum possible flow in the drain piping.


CFR 3280.610 (c)(5) Preassembly of drain lines. Sections of the drain system, designed to be located underneath the home, are not required to be factory installed when the manufacturer designs the system for site assembly and also provides all materials and components, including piping, fittings, cement, supports, and instructions necessary for proper site installation.

Minnesota State Building Code (MSBC) 1350.3400 subpart 2, states in part "Waste piping to the manufactured homes shall comply with the Minnesota Plumbing Code (MPC), chapter 4715. This indicates that waste piping (on-site drain waste lines) of the manufactured home shall be installed and tested to MPC 4715. If the manufacturer of the home complies with CFR 3280.610 for "Preassembly of drain lines" the construction of the drain waste line on-site must follow manufacturer's instructions sent with the manufactured home. If the drain waste lines on-site to not follow the manufacturer's instructions they must be completed in accordance with MPC Chapter 4715. MPC 4715.0100 subpart 27, "Building Sewer" means the part of the drainage system which extends from the end of the building drain and conveys its discharge to the public sewer, private sewer, individual sewage-disposal system, or other point of disposal.

The "building sewer" (from drops under the home to point of disposal) would be required to be tested in accordance with MPC 4715.2820. The manufactured home (from the drops under the home throughout the home) drainage system is required to be tested in accordance with CFR 3280.612 (b). Manufactured home proposed federal installation standards CFR 3285.604 (d) will require the tests of the home drain system be completed after installation of the home at the site of occupancy. MPC 4715.2810 requires a minimum of eight (8) hours of notification prior to inspections or testing from the plumbing contractor to the proper administrative authority. If the proper administrative authority does not appear for an inspection within 24 hours of the notification (excluding weekends and holidays) the inspection or test shall be deemed to have been made, and the plumbing contractor is required to file an affidavit with the proper authority stating the work was completed according to code and required tests were completed and system was free from leaks.

Minnesota Statute (MS) 326.40, Piping work from the factory provides connections to the point of disposal require that the work be completed by a licensed plumber/plumbing contractor or by a person with an unlicensed contractors plumbing bond. A licensed manufactured home installer completing connections to a manufactured home would be required to obtain and maintain an unlicensed contractors plumbing bond.

In conjunction with this bulletin also please refer to manufactured home informational bulletin No. 30 issued in September 1999 (still in effect). Bulletin No. 30 discusses on-site connections and materials and who is allowed to perform some of the connections.

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