How to Replace Water Pipes in Mobile Home

Plumbing in a mobile home is quite different than site-built homes. Almost all the plumbing systems in mobile homes are different in varied ways that you will require not only special knowledge to understand how the systems work but also the skill to repair and replace the various plumbing systems.

Besides, mobile homes don’t always encounter similar plumbing issues as site-built ones. If you encounter a plumbing problem such as a leak, you need to have the necessary information such as where the shutoff valve is to shut down water flow and manage the damage until a professional plumber comes in to fix it.

Therefore, understanding the basic plumbing issues of your mobile home can save your home and possessions from water damage in case a leak occurs. Knowledge of how your mobile home plumbing system works will significantly make it easier for you to determine when and where the problem has occurred and how to fix it before you call in a professional plumber to help.

In this post, we help you learn how mobile home plumbing differs from a site-built home, the various pipe materials used, and how to replace water pipes in mobile homes. So, without much ado, let’s get started.

The Basic Elements of a Plumbing System

Both mobile homes and site-built homes consist of incoming and outgoing pipelines. In older homes, most piping fixtures are iron, but owing to the risk of corrosion and rusting, modern homes have shifted attention to cheaper and safer piping options such as CPVC, copper, brass, and PVC.

Fixtures are also important elements in your mobile home plumbing system. You interact with them on a daily basis. Faucets, showers, toilets, and washing machines are all plumbing fixtures. A problem may occur with any of these fixtures or their lines and understanding how they operate will help you identify the source of the problem in case anything goes wrong.

Plumbing systems in both site-built and mobile homes start with freshwater lines that bring in water. Some of the clean water goes to water heating appliances for warming and from there it goes through dedicated lines to your hot water faucets on your sinks and shower fixtures. The other cold clean water flows through supply lines to service your toilet, taps, shower, bathtub, and washer.

After you use this water, both hot and cold from any of our home fixtures, it goes down the drain. All the drains from your sinks, toilet, bathtub, and showers connect to the main sewer line that exits your home. A clog or blockage in your home’s sewer line can cause a backup of wastewater into your home.

To remove the blockage requires an experienced DIY-er or a professional plumber to do the job safely. Owing to the design of the mobile home’s plumbing system, fixing a clogged drain can be more difficult, especially if it is in the main exit line from home.

In order for the drain lines to drain wastewater correctly, they require ventilation. Air needs to enter the drain line system to help wastewater to drain down into the city sewer line faster and smoothly. However, the location of the vents for mobile homes and site-built homes is substantially different. So, knowing the location of the vents in your mobile home can help you check whether a blockage is what is restricting drain flow.

The incoming and outgoing water pipes, fixtures, and vents in residential and commercial property are what create the entire plumbing system. Regardless, the specific design is not similar in mobile homes in comparison to site-built homes. Knowing the differences will help you discover how your mobile home has a distinctive plumbing system.

What are the Major Differences Between Site-Built and Mobile Home Plumbing Systems?

Mobile homes use the same basics and logistics in their plumbing system design as the site-built homes. However, there are obvious differences between these two. In fact, everything from the material to the location of the pipes and drain venting in mobile homes differs in orientation in site-built homes. Here are the differences in detail:

Piping Materials

The piping materials in mobile homes are often innovative. Moreover, mobile home builders tend to use new plumbing pipes to see how they function. For instance, contractors first used PEX piping materials in mobile homes before they started to use them in site-built homes. Today, PEX piping materials have become common in site-built homes and standard in the plumbing industry.

Site-built homes usually use copper pipes for water supply lines, but in mobile homes, the copper pipes are not standard. PEX and CPVC pipes are common in mobile home supply lines. Copper lines in site-built homes are used for both hot and cold water lines.

Copper materials can last longer when used in a site-built home’s plumbing system. On the other hand, plastic piping materials are cheaper and easier to install. For instance, PVC pipe can be used for both drain lines and some selected supply lines.

Drain pipes carry wastewater out of your home. PVC, cast iron, and chromed brass pipes are commonly used in wastewater lines. PVC is the most likely material to be chosen by experts who know how to plumb a mobile home since it is easier to install. Besides, it will cost less than metal pipes.

Location of Pipes

The places where the piping system passes differ between a mobile home and a site-built one. While in site-build homes the supply lines run through the walls, in mobile homes, the supply lines run under the house.

Under the house, piping orientation can pose a problem, especially in winter as the pipes will freeze. So, depending on the layout of your house, the supply pipes can run adjacent to the subfloor heating ducts or along the edge of the floor. Moreover, your water-based heating systems location may also determine how your water supply pipes enter your home.

Venting of Drain Pipes

Also, the vents for the drain pipes differ between mobile homes and site-built. Vent stacks to allow air into the drainage lines are allowed by law, but cleanouts aren’t. In a mobile home drain line system diagram, vents may be visible on the roof. Often, every fixture in a mobile home has a vent. For example, a sink may feature a vent under the counter.

Cleanouts ad overflows are not often included on the fixtures or outside of mobile homes. This is because these openings are not added in mobile homes plumbing systems thus clearing a clogged drain in these homes is quite difficult. Additionally, the difficulty adds to the reasons to consult with an experienced plumber should you have a plumbing issue in your mobile home.

Common Plumbing Pipe Materials Used in Mobile Homes

Because the plumbing materials in mobile homes are different from those in site-built homes, you may not be able to utilize the same materials for DIY situations. Plumbing materials for mobile homes tend to cost less and are easier to work with. These attributes should not give you the pass to try every plumbing repair or replacement in your mobile home.

Therefore, knowing and understanding the materials you can use on a mobile home plumbing system can help you figure out the plumbing problem your home is likely to have based on the materials used in the supply and drain lines. The following are the common plumbing materials used in mobile homes:

Polyvinyl Chloride (PVC)

PVC is a conventional piping material that can be used in supply lines, drainage pipes as well as vents. PVC is a plastic material that is easy to cut and find replacement fittings for. For instance, you may have seen patches of PVC replacing worn sections of supply or drain pipes.

Moreover, owing to its lightweight nature, it makes working with it seamless and manageable. It is also used in replacing older, black plastic pipes known as ABS that may still be part of older home construction. ABS fell out of use because of its breakability in sunlight.


Also referred to as cross-linked polyethylene pipe, PEX pipe consists of colored tubing which bends seamlessly. PEX is a durable pipe material that has a unique ability to bend 90-degree turns, something rigid pipes cannot do.

Owing to its flexibility, PEX required fewer connections thus creating fewer potential leak sites. Regardless of its flexibility, this material is resistant to temperatures ranging from 320 to 2000 Fahrenheit. It comes in blue, red, and white colors, therefore, you can use blue for cold water and red for hot water for easy identification of plumbing lines.

Even though PEX pipe is still a relatively new plumbing material option, it will cost you less than most other supply line materials such as copper pipe which is not common in mobile homes. And since PEX can be quickly installed by plumbers, requires fewer connections than CPVC, it has become a favorite option for both site-built and mobile homeowners and plumbers as well.


Chlorinated Polyvinyl Chloride (PVC) is specially designed and treated for use in both hot and cold water supply lines. Because of this treatment, CPVC pipe has come a favorite for hot and cold water line piping.

Besides, these pipes can be glued together for a permanent fit. However, plumbers may use grip fittings for future changes. Equally, CPVC comes at a low price and is easy to install making it ideal for supply lines piping in a mobile home.

Common Plumbing Issues in Mobile Homes

Frozen Pipes

The freezing of pipes is one of the common plumbing issues in mobile homes. The main reason for this is that the pipes in mobile homes run under the house making it easier for cold air to freeze the water flowing inside the pipes.

Once the water freezes in one of your pipes, the ice block can cause pressure build-up in the plumbing system until another portion of the supply line bursts. A burst pipe can rapidly pour water into your home to cause significant damage to structural components as well as your possessions.

You can easily keep your exposed water supply pipes from freezing. For instance, you can use heat tape to warm pipes under your house, especially during the cold winter season. With the thermostat on this tape, you will be able to maintain a temperature warm enough to keep your water flowing without overheating.

However, you must keep the tape plugged in the entire time of its use. moreover, when choosing a heat tape for your home use, consider choosing one designed for the material your water pipes are made from.

Clogged Drains

Drain clogs are usually occasioned by pouring or flushing inappropriate waste down your drains. For example, you should never pour grease down your kitchen sink since it will cool and congeal down the drain to cause a clog. Hair in your bathtub or shower drains does the same thing while your toilet can get clogged by flushing non-flushable items like baby wipes and sanitary towels.

Whenever your mobile home plumbing system is clogged, consider using high-pressure water or a plunger to clear the clog. If it proves difficult, call a plumber. Don’t use chemical drain clog removers as they corrode your drains over time or injure a plumber should you call them in to fix the clog.

Leaking Pipes

Leaking pipes can either be hidden or visible. Water damage and molding often arise from hidden leaks in your mobile home sewer pipes or supply lines. Since leaking pipes can cause substantial damage to various parts of your home other than plumbing, you need to repair them immediately.

Fortunately, water damage in mobile homes is restricted to the floor around where the pipe is leaking. This is because the water supply lines usually run under the home. However, this is not the case with site-build homes where the pipes run inside the walls thus water damage can be substantial if a leak occurs.

Pipe leaks in mobile homes also happen in pipe joints. More often, leaks in mobile home plumbing systems come after the home arrives at its final destination. This is because moving the house and the settling process causes stress in rigid pipes thus leaking to leaks. besides, freezing can also cause holes in the water supply lines.

So, once you notice low pressure that you cannot figure out why or you realize that your water bills have shot up than usual, then suspect a leak in your plumbing system. A leak in your mobile home’s plumbing system, whether hidden or visible requires expert repairs. Therefore, call in a plumber to help handle the leaks before it compromises your home’s structural integrity.

Dripping Faucets

Dripping faucets are one of the most common and annoying plumbing issues you can experience in your home. Nothing can keep me awake all night long like a dripping faucet into a metal sink. If you have dripping faucets, the only remedy is to replace the washer in your faucet to stop the drip. If this doesn’t work, then you need an expert plumber to troubleshoot and solve the problem.

Low Pressure

Low pressure in your water supply lines can originate from either outside your home or at an individual fixture. If you are experiencing low pressure in all the fixtures of your home, then consult with your neighbors to see if they are experiencing the safe low-pressure issue. If yes, the problem could be from your local water supply lines, but if not, then consult a plumber to figure out what the problem could be.

If you are experiencing low water pressure at an individual fixture, then you might have an easy-to-fix problem with the aerator. So, clean the aerator and recheck the pressure. If you still have low-pressure call a professional plumber to fix the problem.

How to Replace Water Pipes in Manufactured Homes

Shut off the water supply to your home

Once you have a water leak, knowing where to shut off your mobile home’s water supply will make the difference in experiencing a complete disaster and a small inconvenience. So, look around your house to locate the main shutoff valve and shut off the water to your home.

Ideally, the shut-off valve to your home will be the large valve next to the water hose faucet. Turning it all the way to the right will cut off the water flowing into your home. Check the water at your kitchen faucet or shower to verify that you have completely shut off the water.

Locate the source of the leak

Ideally, you marked where the pipe was leaking before shutting off the water supply. So, get back and assess the extent of the pipe damage. If the pipe is burst horizontally, you need to replace it, but if it is a small hole, then repairing it can still be effective.

Pull the pipe away from the insulation

For easy replacement of the damaged pipe, pull it away from the pipe insulation to find an appropriate way of cutting it. Cut the damaged area on either side for easy fixing of the couplings and the new pipe.

How much will it cost to replace water pipes in a mobile home?

Replacing hot and cold lines in a mobile home of about 1,500 square feet, with a two-bathroom can cost you between $8,000 and 10,000 for metal plumbing pipe like copper. However, for PEX piping the cost will be a little cheaper at between $4,000 to 6,000. This is because the PEX material is cheaper and easier to work thus overall lower cost on material and labor.


Q: What size of water supply lines do I need in my mobile home?

A: Most mobile homes have two sizes of water supply lines; 1/2 – inch and 3/4 –inch. The 3/4 –inch water supply lines are used for piping the main water supply line leading in and out of the water heater. The 1/2 –inch, on the other hand, is used everywhere else in the house.

Q: Do water supply pipes run through the ceiling in mobile homes?

A: Water supply pipes can run through the ceiling in mobile homes and that can’t be unusual at all. However, they have to be carefully installed to avoid freezing because they can cause substantial damage that can cost you a lot more than when the pipes freeze in the crawlspace.

Q: What causes my mobile home to smell like sewer?

A: The main cause of your mobile home smelling like a sewer is the P-trap plumbing fixture beneath your kitchen sink or bathroom. When the P-trap is empty of water or has a crack, it may leak that awful smell you are experiencing in your home now.

Q: What is the grey pipe in my mobile home called?

A: Polybutylene (PB) pipe is a grey plastic pipe that was commonly used in water supply pipes back in the years between 1978 and 1995. However, the use of this material was discontinued because there were reports that the pipes ruptured and caused substantial water damage to homes.


Never let small trailer plumbing issues in your mobile home turn into major disasters that can damage your home and possession. If these small plumbing problems don’t get fixed early enough, they will get worse. Therefore, consider calling a licensed plumber to examine and fix the problem.

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