Fix Your Washing Machine Issues (in a Mobile Home)

We get a lot of questions about washing machines drainage issues. Gurgling, smells, and slow drainage are common because as much as I love mobile homes, the plumbing system design could be better.

The plumbing system in a mobile home is very similar to a site-built home with only three major differences: the size of the pipes, the placement of the pipe and the ventilation design is a bit more elementary.

Manufactured homes have their supply lines installed under the floor then get stubbed up through the floor for most fixtures. Only fixtures that are higher like tubs, showers, and washing machines will have any kind of water supply lines in the wall.

We aren’t talking about the washing machines themselves in this article, just the plumbing systems that supply and then drain the water from the washing machine. If you need help with repairing the actual washing machine this site will help.

Most common Plumbing Issues with Washing Machines in Mobile Homes

New washing machines use less water and work more efficiently. That means they use shorter cycles which needs faster water supply and drainage.

The ventilation and drainage system in mobile homes could handle all these new washing machines a lot better if the builders would change or upgrade just a couple of things.

For general plumbing issues in mobile homes our article, 5 Common Mobile Home Plumbing Problems, will help.

Why do Washing Machines Have so Many Problems in Mobile Homes?

In our article, Diagnose and Repair Venting Issues in a Mobile Home Plumbing System, I used the image below to describe why manufactured homes have so many issues with their washing machines.

Before we begin, please understand that everything in this image meets the HUD code and has worked for millions of manufactured homes for decades. In this image, we are looking at the backside of the wall in a laundry room. The white box is the washer box where the drain pipe goes and where the hot and cold water lines are attached. The little black thing on the right pipe is a very generic auto vent.

For a site-built home, the venting in the image would be different. The white drainage waste pipe would be 2″ (mobile homes use 1.5″) and the auto vent probably wouldn’t be used at all. Instead, a vent stack going out the roof would likely be used to give the washer adequate ventilation for drainage. If a vent stack wasn’t used a Studor vent would be and it would be placed where the black auto vent is except that pipe would rise above the washer box, again to give the drain line better ventilation.


I’ve previously stated that most mobile homes could use a larger drain line for the washing machine. The 1.5″ pipe cannot handle these newer washing machines.

If you are remodeling or just have a chance to upgrade the plumbing for your washer we recommend the following:

  • Replace original drain pipe a larger diameter (2″ minimum)
  • Give the washing machine its own stack vent that raises out of the roof. If that’s not possible relocate the air vent so that it is above the drain line’s highest point.
  • If a new stack or air vent relocation isn’t possible, replace the generic air vent with a Studor Brand

The Washing Machine Shakes the Whole Mobile Home

Shaking, rattling, and rolling should be reserved for the dance floor. If your washing machine is making the whole house do the jitterbug it’s likely unbalanced, unlevel, or over-loaded.

Loads are Unbalanced and Over-loaded

My husband is the world’s worst at overloading and balancing a load of laundry. We have a newer top-load with no agitator. He just throws clothes in all willy-nilly and doesn’t know when to stop. Bless his heart, at least he tries.

Unbalanced means the load in the machine is heavier on one side of the tub. This is common with heavy towels and jeans. As you load the machine try to go in a circle and equalize the weight.

Frozen water lines also affect washing machines. We have a complete guide on using heat tape to keep your mobile home water lines from freezing.


Unlevel requires a little more work. Most washers have self-leveling back feet and adjustable front feet that can be raised and lowered as needed. If your mobile home is unlevel, and many are, or the floor is warped you’ll need to keep an eye on this more often.

adjusting feet on  a washing machine

Just place a bubble level on the top and sides of the machine and screw or unscrew the feet till you get all sides equal. If the feet doesn’t hold position you may need to replace them. The lock nut may be bad.

There are also anti-vibration pads you can use on your washer and dryer that may make it a bit quieter.

Washing Machine Fills Up Very Slowly

If it takes a long time to fill up your washing machine you probably want to do two things: replace the supply lines to your washing machine and clean or replace the filter screen on the back of the machine.

Replacing the supply lines isn’t really going to help your machine fill up faster unless there is gunk in the hoses but anytime you remove the hoses it’s a good time to upgrade to metal braided supply hoses.

There is a couple of common noises that happen when a washing machine is filling up. If you hear thumping under the home or in the walls that sounds like solid material hitting another solid material you may just need to strap the supply lines under the home better.

If you hear something that seems to be coming from the inside of the water supply lines you may be able to install hammer arrestors to stop it.

Related: 7 Tips to Reduce Moisture Problems in Manufactured Homes

Typical Washing Machine Drainage Issue in a Mobile Home

As stated above, one of the biggest reasons homeowners face drainage issues because the drain pipe in the mobile home is too small. When ventilation and drainage pipes are too small it doesn’t allow enough air to enter and equalize the atmospheric pressure in the pipe.

Washing Machine Drainage Issues: Loud Thumping and Gurgling

Loud thumping and gurgling during the drain cycle of a washing machine is a sign that the drain pipe is too small and/or the vent line isn’t adequate.

To fix this you can try replacing the auto-vent. We always recommend Studor brand auto vents (also called air admittance valves).

Another fix may be replacing the 1.5″ drain pipe with a 2″ but that’s a lot more difficult.

Questions and Answers about Washing Machine Drainage Issues

We’ve answered over 6,000 requests from readers about mobile home repair and remodeling issues over the last 7.5 years! We also answer most posts in our Facebook group page called Mobile Home Living: Repairs and Remodels.

Below are two questions that we’ve received that best reflects common plumbing issues with washing machines in mobile homes.

Sewer Odor from the Laundry Room

One reader sent us the following question about her washing machine drainage issue in a mobile home:

We are having a sewage odor problem that comes and goes. It’s worse in the laundry room and the air conditioner distributes the smell all over the house. We have a brand new septic system and only the kitchen and the toilets drain to the septic system. Everything else drains to the backyard as gray water. There is no odor where the gray water drains, and there is no odor under the house. A plumber fixed the ventilation stack about 9 months ago. But within 2 weeks we had no more odor problems – until about 3 weeks ago. Since then, the plumber has come back out, but we are still getting the smell. Any ideas?

It sounds like the water in your p-trap is getting siphoned out of washer’s drain vent. If that isn’t the culprit, check to see if the AC unit drain is tied into the sewer.

AC drain lines do not have a p-trap (unless installed). Which can allow odor to escape.

 Washer Backup into Bathtub in Mobile Home

This next question is a good example of how everything in a home is connected via the drainage trunk.

We own a double wide with two bathrooms. I took a shower and then did the dishes and everything drained fine. But when we did a load of laundry and it started draining all that water come out of both bathtubs!

It left about 2-3 inches of dirty laundry water in both of the tubs. They didn’t drain at all for almost 10 hours. The water in the toilets went missing, too. When I tried to fill the toilet bowl and you could see the water rising inside the tub.

The kitchen sink doesn’t seem to be affected. I have searched and searched for answers. Help!

It sounds like you have a stoppage. As a result, this would make the drains slow since you aren’t getting the pressure equalized in your traps. That, in turn, creates a vacuum that pulls the water out of your toilet.

When you wash clothes you’re using a lot more water than usual. A clog down in the trunk line can backfill until it comes out of the tub drains. The water leaves the toilets because the trunk is full of water so it cuts off the toilet’s ventilation. This, in turn, siphons out the toilet.

You’ll need to find where the clog is and snake it out. You can try a residential snake available at Amazon here (affiliate link) but sometimes it takes an industrial snake that shoots high-pressure water so you’ll need to hire a plumber.

They are around $25 at your local home improvement store or order one from Amazon here (affiliate link).

Washing Machine Wastewater in the Yard

Rural mobile homes with septic tanks are often drained into the yard. This practice should not occur for a few good reasons.

Draining the water into the yard can cause a variety of issues that many homeowners don’t think about. First, the drain usually ends up draining close to the home so water ends up under the home. That amount of water cannot be dried up with a few vents in the skirting. Mold and mildew love dark wet places. It can also cause condensation issues with your furnace and ductwork.

Second, wet ground is soft ground which doesn’t hold weight very well and manufactured homes are pretty heavy. Third, grey water is not safe. It can introduce a variety of chemicals and elements that shouldn’t be close to the home. There’s a reason local code requires 100 feet between septic and water source.

Many homeowners drain wash water into their yard because they think their septic is too full or it will keep the septic from getting full. This is not true. Septics seep out liquids so if a few loads of laundry fill it up it’s far past time to have it pumped. Water floats atop solids.

Summary for Common Plumbing Issues with Washing Machines in Mobile Homes

There are several common plumbing issues with washing machines in mobile homes. Shaking the house when the machine spins and washing machine drainage issues are the most popular.

As always, thanks for reading Mobile Home Living!

This article was originally published on Jul 7, 2017 and updated on May 10, 2019.

Disclosure: Answers and advice about fixing mobile home venting issues should not be used as a substitute of an expert. Please contact a professional to inspect the issues in person.

Featured Image Source: CottonCopper

20 thoughts on “Fix Your Washing Machine Issues (in a Mobile Home)”

  1. I have a 1969 mobile home in good condition I want to change the washer and hookups in th bathroom to the second bedroom to make it a laundry room it shares the wall with the back of the sink toilet and tub/ shower is this do able?

  2. How do I plumb up the sewer line under the house how do I put it together I just got a brand new double wide I need to know how to plumb up the sewer and what line under the house or for the water so they got two in the middle of the house one is white and one gray

    • Hi Jason,

      Congratulations on the new home! You’re gonna need to hire a plumber. This is not the kind of job an unlicensed person should be doing. You have to know proper grade for one and for two a plumbing system is an extremely complex system that includes 3 different subsystems that must work together. The dealer you bought the home from should be able to help you (and usually installation and setup are added to the loan). Best of luck!

  3. About a year ago, we started getting sewer smell in our home. Especially when using the washing machine. We had the septic tank pumped out last year, which was not full at the time so that wasn’t the problem…and the smell remained. Tried changing out the caps on the vent pipes. This helped a lot. But the smell has recently come back with a vengeance! The horrid smell comes up through the furnace and floor vents now. We do not use the furnace, so we covered all the floor vents. This has helped but not completely. And at the furnace it is nauseating! I had someone spread lime underneath the mobile home but that only took the smell away for that day.
    When my son and husband crawled under the home, they said it did not smell like sewer nor could they find any leaking pipes. suggestions??

    • Hi Mallissa,

      You may need to make sure your sewer lines aren’t open under the home first. If it’s not that, make sure your septic tank or waste line is not full or backflowing. If it’s not that, you’ll want to check the vent system and make sure there is no cuts or separations.

      It’s def fixable, it’s just going to take some sleuthing to see which issue is causing it. It’s probably going to be one of the 3 I mentioned. Best of luck!

  4. Hi. I am renting an older mobile home and it has major problems. If the vent cap on the outside of my home is tight ALL my water a sewage fills up in the bathtub. It was snaked and there was no obstruction. If I leave the cap loose everything drains out of the pipe into my yard. I don’t know what to do. It started with the washing machine draining and all that water filled up the bathtub..Thank you for any help you can give me.

    • Hi Linda,

      If I’m understanding you correctly, your vent stacks should not be capped at all. It has to allow the gases to escape and to keep the system in balance and ‘breathe’ so it has to be left open.

      Take the cap off and you’ll be fine. Rain will get in, as will birds, but you can put a screen over it to keep the birds out if you must (it’s fine without it though) – the rain is minimal and doesn’t hurt anything at all.

      The washing machine was probably vented to go out into your yard. It’s not legal in most places but many people do it to keep the sewer from filling up. It’s common out in the country or on shared septic systems.

  5. Hi. Every time I use the kitchen sink I have to go back to the bathroom and flush the toile. If I don’t we won’t get rid of the nasty rotten eggs smell that starts to fill up the mobile home. My ventilation/ pipes are along the inside, against the wall. From the kitchen through the living room and my son’s bedroom to the bathroom. Any thoughts why I can’t just start washing dishes without getting that awful smell?

    • Hi Victoria,

      It definitely sounds like something is sucking your traps dry. There’s a partial clog holding water in the trunk line or an auto vent may be going bad. Either way, your system is off. First, look for an auto vent and replace it. Then start snaking.

      Best of luck!

  6. hello,
    thank you for this great newsletter and ask an expert, cause where i live, no one has heard of a “stink pipe” or “vent” or “stack”, etc. i am well past my irritated stage with this problem. i have read your article on sewer smells. being a female with a husband who doesn’t know much, i’m left alone to to investigate the problem and, well, like i said, i’m very irritated right now.
    my issue is – every time i do dishes, the sewer smells come to the kitchen, living room and well, all over. i’ve put zeps heat down and allowed to soak over night in all drains, poured hot water the next morning, but nothing happened. where could this clog be? i can’t see a pipe on my roof unless i get up on ladder and it’s like “heck” trying to get anyone to come out who knows mobile homes! (Screams). if the pipe on roof is clogged, how do i unclog it? if it’s not the pipe, where do i begin in the house? also, how do i put an auto vent in bathroom or kitchen? is that simple? i look forward to your reply. thank you for allowing me to vent – ha, pardon the pun!

    • Hi Laura,

      I would try installing an auto vent on your kitchen sink first. If that doesn’t work then start snaking out the vent stack and the waste lines. Most of the time it’s a grease issue at kitchen sinks though. Best of luck!

  7. Hi Nani,
    I’m not sure what that could be other than mildew or mold that is growing under your carpet. I’d lift it from a corner and see if you can see anything either on the carpet pad or rotted wood on the subfloor. I’m still doubtful that it could be that strong to follow you. Maybe look under the home for a dead animal?
    This probably wouldn’t be a manufactured home issue, just a home in general kind of issue since manufactured homes use similar materials as a site-built home (even if the material is cheaper).

    I’d definitely have someone check out under the home, vents, and under the carpet. Best of luck! Let me know how it goes!

  8. Drainage problem with the washing machine and kitchen sink. The drain pie was cut and drains on the dirt on the side of the mobile home by the kitchen. It’s flooded all the time. It gets under the house too. The rain makes it worse. I saw a 3″ x50′ corregated drain pipe at Lowe’s for $29. Can I attach that to extend it out into the property to drain out there to move the water away from the house? Do you have any other suggestions? What are the possible damages this may have caused already? The place looks bad and is falling apart. Thank you.

    • Absolutely! A true ditch with a metal grate is also a good idea. This will keep cars from crushing it too. We have a couple across our driveway for rain diversion – all we do is clean the culvert/ditch out every couple of months.

      Best of luck!

  9. I bought a 95 manufactured home double wide. It has what I call a “fresh air fan” in the family room ceiling that is operated by a switch on the wall. When I bought the home the fan assembly and motor was missing and I cannot find a replacement anywhere. The fan vents straight up thru a roof vent. I would like to find a replacement motor and fan assembly or a similar size top venting fan so I do not have to replace drywall. Do you know where I could find a replacement, I can only seem to find bathroom fans. I have had these in my homes before so I know there are commonly installed. Just not commonly found to replace.

  10. Hi, we just bought one of those great craigslist mobile home finds. We are going to be remodeling throughout. It has an island range with a range hood over it, and I’d love to customize it to a farmhouse look. Is it possible to hang a heavier hood cover in a mobile home? I’d hate to pull the roof down on us. Right now it is basic generic straight hood cover. I would love to do something like this.


    • Hi Charlote,

      A nice hood really does make a kitchen stand out! Great idea! You shouldn’t have any problems as long as the hood isn’t too heavy – just make sure it is secured into studs. I’ve seen a homeowner build their own hood cover just like that with mdf (or maybe it was thin pine board) and trim.

      Best of luck!

    • I have a 2007 manufactured home. In the last year I have had an awful smell in my one bathroom and sometimes in the kitchen. I had a plumber come out and he changed the toilet rings, thinking maybe the smell was coming from the toilets not being sealed. He also checked under the house and found no leaks. I have vent caps that are under all the sinks, which I have replaced. The new caps helped for a bit but the smell is back. The drains all have water in them. I can say that if I run water down the tub it seems to help for about a day but then the smell is back. I’m at a loss. I live in a mobilehome park.

      • Hi Dana,

        It sounds like something isn’t venting right. Even with auto vents, there is a chance that one of your traps is getting sucked dry. That allows the odor to enter your home. The tub is especially susceptible to going dry because of pipe them as inline traps (trap in the horizontal pipe).
        Best of luck!

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