How Does Septic and Plumbing Work for Manufactured Homes?

Have questions about your manufactured home plumbing? Find out where the pipes are, the type of plumbing used and more!

Plumbing and septic systems made for manufactured homes are slightly different than site-built homes. You will still have your piping system, waste disposal system, a water heater, pipe venting and water valves just like a site-built home. The main differences in these systems for a manufactured home include:

The utility room of a manufactured home featuring dark wood like floor and white walls.

Who Regulates Plumbing Codes for Manufactured Homes?

The requirements for plumbing systems for manufactured homes are governed by HUD Code and are followed to ensure proper installation and construction. Local codes for plumbing may take precedence over HUD Code when it comes to the connection of the plumbing systems to site connections for septic and water supply. Check with your local home consultant to see what codes your plumbing and septic will be built to.

Where are Pipes in Manufactured Homes?

Manufactured home plumbing runs through the floor of the home. Your pipes are located within the belly board, which is sometimes called the bottom board, and is surrounded by insulation. The belly board closes in the insulation around your plumbing and keeps everything in place under your home’s flooring system.

Pile of pipes used for plumbing in manufactured homes.

The Type of Plumbing Used in Clayton Built® Homes

The pipes used in new Clayton Built® homes are durable and are made of PEX plumbing. If you check your plumbing, you’ll see two different sizes of pipes. The smaller pipes are your water supply lines and the larger pipes are drainage lines.

Some of the advantages of PEX plumbing include:

  • Resistance to scale, which is the build-up of minerals such as calcium and magnesium
  • Resistance to chlorine
  • Non-corrosive
  • High heat resistance
  • Easy to install
  • Less expensive than metal piping

Because your plumbing is durable, it will last you for years to come and will not require as much repair. Because it is easy to install, we can cut the building time and pass the savings onto you.

Manufactured home with blue siding and a stone front porch with a large front yard.

Myths About Manufactured Home Plumbing Systems

Plumbing vents help drain lines work by drawing in air from outside of the pipes to create the proper pressure levels in the pipes for waste to flow.

Contrary to the belief that manufactured homes are not vented well, or even the myth that they do not have vents, all manufactured homes are required by federal building regulation to be properly vented.

Venting that you will find in your manufactured home includes a direct vent through the roof (VTR). The VTR allows multiple fixtures in your manufactured home to be vented. Because vents help the pressure in your plumbing by helping regulate air flow in pipes, sometimes vents can be located too far away from certain fixtures to aid those fixtures. If the VTR is too far away from a specific fixture, a mechanical vent is installed to ensure your home plumbing is properly vented.

Another myth about manufactured home plumbing is that homes do not have clean-outs. Site built homes and manufactured homes alike have clean-outs that are used to clear clogs. Plumbing code for manufactured homes requires a clean-out where a plumbing fixture turns enough times to create a 360-degree angle before getting to the main drain of the home. While the main clean-out is often outside the home and can be found in your yard by looking for a sewer cap, they can be located all over the home. Clayton builders typically place clean-outs below each vanity and sink and at the washer box connection behind the access panel.

Clean-outs can be placed in different locations of each individual home depending on the layout and location of the bathrooms, laundry room and kitchen, but a clean-out will be installed above the floor in these areas and in the plumbing below the floor system for access.

Manufactured homes are required by federal building standards to have clean-outs. The federal HUD Code does have requirements for where clean-outs should be placed, but Clayton takes it a step further. New Clayton Built® homes have a clean-out below each sink fixture, whether it is necessary or not, to allow homeowners access to the drainage system.

Prior to your manufactured home on-site construction, you can also ask if an exterior clean-out can be included in your property preparation with the construction of your waste disposal system.

Where are my Shutoff Valves?

You will find shutoff valves for your piping throughout your manufactured home. Your main water supply shutoff valve in a manufactured home should be in the utility room.

You may also find a toilet shutoff valve in your bathroom underneath the toilet tank. This can come in handy if you have issues with a clogged toilet. It is also handy for regular toilet cleaning.

You may also have a kitchen shutoff valve under your kitchen sink or a bathroom sink shutoff valve under your sink in the bathroom.

Bathroom of a manufacture home featuring patterned accent wall and a double vanity with a bench.

What Kind of Drainage Do Manufactured Homes Have?

Mobile homes will have drain lines that extend under the home from below the bathroom to the sewer line that goes into the ground.

Since manufactured homes are nearly complete when they leave the manufactured home building facility, the drain lines will already extend through the belly board of your home when it arrives to its final destination for on-site construction. This is when an on-site construction crew will connect it to your waste removal system, which will be either the public sewage line or a new septic system installed for your home.

A septic tank being buried during on-site completion of construction for a manufactured home.

Do All Manufactured Homes Have Septic Tanks?

Your waste removal system will depend on your home destination. If you use a public sewer system, your home waste removal system will consist of plumbing running from your home to the public sewer system. However, if you do not use a public service, you will need to have a septic system that is approved by your local municipality.

A possible system that you may be told to use is a septic tank. When looking at septic systems, the septic tank/absorption field system is a commonly used option. Waste would drain from your home into a septic tank that is buried underground which will be installed during the set up and installation of your manufactured home.

Waste sits in this tank to settle and separate out into sludge, scum and effluent. Effluent, the relatively clear waste from your home drainage, will flow out into the drain field where leftover contaminants are mostly removed and waste water will drain into groundwater.

These septic tank systems need periodic pumping to remove the sludge and scum that remains in them. Regular inspections are recommended as well.

Now that you know the differences in plumbing between manufactured homes and other homes, you can better look out for potential drainage issues, clogs and leaks. To learn more about how manufactured homes can be different than other homes, check out more information about the requirements the federal government has for your home water heater.

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