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 system 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, change out the generic air vent with a Studor Brand air vent.
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 so 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.
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.
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 sure 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 and that’s just here on the site. We also answer every email and we have a Facebook group page called Mobile Home Living: Repairs and Remodels that we are active in. Here 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 and within about 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. If it is it will need to be disconnected as it doesn’t have a p-trap and will allow the odor to escape.
Washer Backup into Bathtub in Mobile Home
This next question and answer have a lot to take in but it’s a good example of how everything in a home is connected via the drainage trunk. If I had to guess, the washing machine and the master bath are ventilated together.
We own a double wide with two bathrooms. I took a shower and then did the dishes and everything drained fine. However, when we did a load of laundry and it reached its spin/drain cycle all that water started coming up into both bathtubs!
It left about 2-3 inches of water in both tubs and you could tell it was dirty laundry water, they didn’t drain at all for almost 10 hours. The water in the toilets went missing gone, too. I let some water into the toilet bowl but as that water went into the toilet bowl 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 washed clothes you probably used a lot more water than you usually do and because you have a clog it filled the trunk line up until it came out of tub drains. The water gets sucked out of the toilets because the trunk is full of water so it cuts off the toilet’s ventilation which 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 but it really needs to stop 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.
Most homeowners drain wash water into their yard because they think their septic is too full to handle it or that it will keep the septic from getting full. This is not true. Septics seep out the liquid so if a few loads of laundry fills 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: Any answers to questions and advice posed about fixing mobile home venting issues and any recommendations or information provided herein should not be used as a substitute of an expert or any relevant professional that has inspected the issues in person.