Plumber repairing pipes with wrench

5 Common Mobile Home Plumbing Problems

We get a lot of questions for mobile home plumbing problems like slow drainage, foul odors, and backflow.   Some of these issues can be fairly easy fixes for a homeowner with an average DIY experience.

With the information below you should be able to better pinpoint what is causing your mobile home plumbing problem, why it’s happening, and what needs to be done to fix it. 

You can learn more about manufactured home plumbing and drainage and ventilation issues here.

We also have an article about the basic of plumbing In manufactured homes. 


Why Mobile Home Plumbing Problems are So Common

Mobile home plumbing problems are common for a couple of reasons: the materials used in the system are usually made of plastic or softer metals because they are lighter and more affordable and the pipes are smaller and not as securely placed as pipes in a site-built home. We’ve seen pipes just laying under cabinets more than once. 

Poor ventilation is another big reason for many mobile home plumbing problems. Most homeowners know about their home’s water supply lines and drainage lines but aren’t so familiar with their plumbing’s venting system.

In fact, the majority of questions that we get from readers usually involves either a stoppage or a venting problem. Read our first Ask a Mobile Home Expert article about venting issues and sewer smells here.

5 Common Mobile Home Plumbing Problems

We cover the 5 common mobile home plumbing problems below. We attempt to explain what causes the problems and what you can do to fix them.

1.  Thumping 

Thumping can occur when water is running or when it’s draining.

What to do When you Hear Thumping While Water is Draining
mobile home plumbing problems - strap

Hearing thumping in your walls can be a bit scary. Oftentimes, homeowners won’t even associate the thumping they hear with water or plumbing.

Thumping sounds are a sure sign that a mobile home has a ventilation issue supply and drain lines.

If you do hear thumping while water is draining it is likely a ventilation issue.

Unfortunately, venting issues are complex and in the majority of cases, you will need to call a professional. With that said, you can do a couple of things so we’ll get you pointed in the right direction so you save time and money and can hopefully get everything fixed in one call.

When you hear thumping when a sink or washer is being drained you probably need to strap your drain lines better under the house.

mobile home plumbing problems -

Thumping when Water is Running

If you hear thumping when your water is running it is likely from your water lines not being strapped properly and it happens a lot. In lots of older mobile homes, you’ll find water supply lines run through cabinets or floor joists without straps.  

There is a product called hammer arresters that will help but a plumber will need to install it. This Family Handyman article can explain more. 

2. Slow Drainage

A slow drain in a bathroom sink will probably be hair build up on the popup. Check the drain plug and the metal bar attached to it. 

Snaking the Drain Lines

Snakes come in many different sizes but they all work the same: they snake through the drain line and pull or push clogs through. Hand snakes are great tools for a homeowner when there’s a small clog but there are some commercial snakes that professionals use that will clear anything. You can buy a hand snake for less than $30. 

plumbing snake - mobile home ventilation problems - ask a mobile home expert series
This snake is available at Amazon for $26.


Click here to learn more about unclogging a drain.

Be sure to snake out each point that you are experiencing issues.


3. Backflow into Bathtub when Toilet is Flushed

When water flows into the tub after flushing a toilet you are likely experiencing a clog in your drain line.

It backflows into the tub because your tub is the lowest point in your system. Water levels out and always find the lowest point first, that is usually a bathtub in a mobile home.

mobile home plumbing problems - toilet auger
Toilet Auger clears clogs easily.

To fix backflow issues that occur after a flush, you will need to use a closet auger. These are similar to a sink snake we mentioned above. It’s essentially a cable and rod system that works together to drill a clog out toward the sewer.

If you aren’t dealing with noise, smell, or other issues it’s probably just a stoppage.

Read our mobile home bathroom guide here to learn more about mobile home bathtubs.


If the backflow problem is not caused by a stoppage, you may have a ventilation issue. Try adding an additional vent for the master bath sink, tub, and toilet (tie them together on a single waste line).

Another issue could be poor grade on your drain line. You’ll want to get the T-branched and graded properly. You need 1/8″ of a grade for every foot of pipe (if it is 3″ or 4″ pipe). Also. make sure it doesn’t have any dips in it. You’ll want to strap or hang it every 4ft, if possible, or build a stand every 4ft to keep a steady percentage of fall to the sewer tap.

ask a mobile home expert - mobile home plumbing ventilation problems -


3. Foul Odors

Foul odors can be caused by several things but it usually always means something isn’t working as it should.

Bad Auto Vent 

The most common is a bad auto vent. Older auto vent springs may stop closing themselves off properly which allows the foul odor through.

Bad Wax Ring

Wax ring under your toilet will be leaking but won’t be visible. If this is the case, unfortunately, sewer water is slowly building up under the home.

Dry P-Trap

A partial clog could be blocking a vent that is causing water in your sink traps to be sucked out. A dry P-trap allows the smell to come through.

If it’s coming from the drainage/waste line you probably just need to snake it out really well. 

Pipe Separation

You could have a drain pipe pulling apart and allowing leakage to collect under your home.

mobile home plumbing problems - aerator parts
The many parts of a sink aerator. (source)

4. Low Pressure


Aerator Clog 

Low pressure in a mobile home is usually going to be an aerator clogged in your sink screens. A quick clean or an inexpensive replacement should fix the problem. 

Pressure reducing valve may be partially clogged.

There are valves, filters, and screens that can get dirty or clogged in several places throughout a plumbing system. Be sure you understand where they are in your home and know how to clear them.

Galvanized Pipe 

If you have galvanized supply lines slowly close off with mineral buildup which causes low pressure. Replacement is about all you can do if this is causing a mobile home plumbing problem.


mobile home plumbing problems - leaks


5. Leaks 

Leaks aren’t just mobile home plumbing problems, they are common in all homes but because mobile homes tend to have cheaper materials they can be more common.

Shower Head Leaks 

Shower head leaks are a common mobile home plumbing problem. Moving a shower head around causes leaks that only occur when water is being run through the head so homeowners don’t catch them until water damage appears on the wall or floor below. Fixing it will require a professional so it’s important for homeowners to be aware of the problem and keep an eye on the shower heads.

mobile home plumbing problems - Old Style Utopia Stem & Bonnet

Faucet Leaks 

Faucet leaks in the kitchen are usually from the connectors where the faucet attaches to the main supply line. In mobile homes, these connectors are made of plastic which loosens up over time. They can get bumped under the sink a lot, too.

See how this mobile home bathroom wows. 

We Haven’t Forgotten Frozen Pipes

We have an entire article dedicated to frozen pipes in mobile homes because I suspect it is the absolute most common mobile home plumbing problems in the nation.


Inspect Your Entire Plumbing System Twice a Year

These 5 mobile home plumbing problems are fairly common in older mobile homes but they occur in newer manufactured homes, too. Inspecting your mobile home is important regardless of age. Use this mobile home safety inspection checklist as a guide at least twice a year. 

Inspect Under the Home

Being a proactive homeowner is vital for a healthy home. We should all inspect the entire plumbing system at least twice a year. A thorough inspection includes going under the home with a light and looking for loose pipes, drips or pools of water, and foul odor under your home. 

Inspect Around and Under Sinks, Toilets, and Tubs

Inspecting the walls and floors around your sinks, tubs, and toilets can save you a lot of headache in the future. Feel for wetness or softness. If you store stuff under your sinks make sure you stay away from the pipes.

Finally, you should make it a habit to check your sink aerator screens when you replace your furnace’s filter.

That’s our 5 most common mobile home plumbing problems and their causes and fixes.  While you should always call a professional before you do anything extreme, you may be able to save yourself a little money by doing simple things like snaking a drain or cleaning the aerator.


Thank you for reading Mobile Home Living!

16 thoughts on “5 Common Mobile Home Plumbing Problems”

  1. We have a brand new mobile home, and after having the tub, sink, and toilet back up twice in less than 2 weeks, we had our local sewer/drain company snake a camera through the plumbing. Unfortunately, we soon discovered the problem … two very large deck screws were driven through the floor and right through the pipe that our toilet drains through resulting in toilet paper getting stuck on those nails causing a backup. Two options for repair include cutting the vapor shield underneath the home to cut out the pipe and replace, or cutting out the floor above the pipe and going through the floor so as not to disturb that vapor shield. Concerns with cutting the vapor shield are that it will create a whole host of other problems from a shoddy repair that will make it an easy access route for rodents, and also we live in Summit County Colorado at 10,000 ft. where the temps are really low and we are buried in snow for 6 months. Your thoughts on the best way to repair this?

    1. Hi Tammy,

      You can buy patches for your belly board so I’d definitely go up instead of down as it’ll be a lot less work. Just have the plumber slice the bare minimum or cut out a hole the exact size as a belly board patch (they have patches with zippers on them so you can access the area again without having to cut the material again). You can read more about belly board repair here.

      Best of luck!

  2. Hi I have a double wide the master bathroom drains fine but everything drains slow or backs up and when use the washing machine or the dishwasher I backs up in one of the bathrooms. I’ve looked under the trailer and the master bedroom is on side of the line by itself and everything else is the other side together.

    1. Hi Justin,

      Your house probably has a 1.5″ stub up for the washing machine. Our new code requires 3″ so the small pipe size is making it airlock itself. Depending on your local code you may be able to get by with draining your to the very end of your drain line or completely separately and into your yard (if it’s legal to do so). Good luck!

  3. thomas robert jarmusz

    i have a leak underneath my kitchen faucet ,now i noticed one of the smaller pipes has a dripping i have buckets underneath pipes very wet under sink trying for help or advice?

    1. Hi Thomas,

      You will need to find the leak and replace the faulty part. The smaller pipes are your supply lines so I’d check the connection between the supply line and the faucet. The fittings can go bad. Usually, it’s less trouble to just replace the entire faucet if it’s something from the faucet. You’ll need to find someone that can do this for you because leaks can damage a home quickly.

      Best of luck!

  4. I purchased a used mobile home and after installation we found that the drain pipe along with the cover popped up about an inch from the shower floor. Can I just push it back down?

    1. Hi Sarah,
      It depends. This could signify that separation has occurred. Is there any way you can get under the home and track that pipe? Or at least do a water leak test (drain water and then go under the home and look to see if there’s any water). You’ll need to cut the belly wrap but there are patches and tapes to fix them back. Some times the p-trap is directly under the tub and connected to the sink or toilet so a separation could be bad.
      Best of luck!

  5. I have a sewer smell in my 2016 doublewide mobile home. I have tried everything down all my drains. Checked under home and septic tank. Please i need help

  6. We just purchased a mobile home and while replacing the tub with a shower stall we noticed there was no P-trap under the tub or anywhere in sight. We are hesitant to install one, as we think it will freeze up with the cold Northeast nights, but wonder if we will have foul smells coming in through the line without one,

    1. Hi Tony,

      You def need a p-trap. If the home is original there may be an inline p-trap meaning it isn’t right under the tub but closer to the tie-in to the toilet before hitting the trunk line.

      Also, if possible use 2” to the tie-in (assuming the origittub has 1.5”).

      Best of luck!

  7. I live in a 2010 mobile home with a septic tank. When I use my toilet, I can hear water gurgling.
    There doesn’t seem to be any water leaking from the toilet. There is a second shower next to the toilet but is not used because there are two bath rooms in the house. We went away for six weeks and when we returned the gurgling started.
    Any suggestions as to what it might be causing it?

    1. Hi Steve,

      I answered your question but then my system said I didn’t so I’ll try again. I think the water in your shower’s p-trap evaporated and that airflow is causing an imbalance in your system. You should be able to get it equalized with by running water in the shower and letting that p-trap get full and balance out and maybe installing an auto vent on that part of the system (sink if it’s connected).

      Best of luck!

  8. Hi. Every time I go to do the dishes way up front. The bathroom gets to smelling like rotten eggs and starts to make the whole trailer smell like it. I have a 1965 Rembrandt. 2br single wide. My pipe drains are along the inside walls. Can you explain?

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