Learn how to diagnose and repair poor drainage and other ventilation issues in your home’s plumbing system. Issues such as foul odor, gurgling, and slow drainage may be repaired quickly and easily!


Since plumbers are expensive it pays to learn how to fix plumbing issues yourself. At the very least, understanding more about your home’s plumbing system can help you save money when hiring a professional.

Learn more about manufactured home plumbing with our article Plumbing In Manufactured Homes: The Basics.

Note: Your state and local plumbing codes will determine the exact requirements that your manufactured home must meet when it comes to plumbing (and electricity, additions, foundations, decking, roofing…basically everything). While HUD sets standard manufactured home building codes on a national level, your state and local laws will take precedence. 

Manufactured Home Vs. Site-Built Home Plumbing

There are a few differences between manufactured home and site-built home plumbing systems.

Plumbing pipes, or lines, are typically placed under a manufactured home and stubbed up through the floor while site-built homes usually have their pipes placed inside the walls. Getting to the pipes is much easier in a manufactured home. The drawback is that pipes ran under a mobile home are more prone to freezing but that issue can be easily fixed.

Manufactured homes typically do not have clean-outs or overflows like a site-built home. The lack of clean-outs can be troublesome when tackling trunk line blockages (technically this is not a ‘mobile home’ issue, but more of a property preparation issue).

Manufactured homes have played an important aspect in the evolution of modern plumbing. New products are often installed on factory-built homes long before they make it to the traditional housing market. PEX, a now favorite product of plumbers worldwide, was first tested and used in manufactured homes.

The 3 Basic Elements of a Plumbing System 

All home plumbing systems, whether in a manufactured or site-built home, have three main elements: supply lines, drainage lines, and ventilation.

Your supply lines are completely separate from your drainage and ventilation but your drainage lines and ventilation are typically together. All three of these elements work together – if one part of the system is broken the entire system is broken.

This video from Home Dept explains how a basic plumbing system works:

Supply Lines

Supply lines carries water into and throughout your home.

Leaks around connections will be your biggest concern with supply lines. Frozen water lines is another big problem that manufactured homeowners face. You can learn how to repair both issues on our manufactured home plumbing basics article. 

Drainage and Ventilation Lines 

Drainage lines carry waste water out and away from your home. We explained drainage in our first plumbing article, Plumbing in Manufactured Homes; The Basics:

Drainage lines use gravity, traps and ventilation to ensure the optimum waste removal and keep gases and fumes from building up and releasing. Think of this as a completely closed system with positive and negative vacuum or pressure. All the parts have to work correctly to allow the system to do what it is designed for. Without the proper positive or negative pressure acting as a vacuum in the pipes the waste won’t go where it’s supposed to, it can back-flow instead.

Diagnosing Poor Drainage and Ventilation Issues

There are a few signs that will clue you into drainage or ventilation issues.

Signs of Poorly Vented Plumbing Drain Lines:

  • Slow Drainage
    • Slow waste water drainage is one of the first signs of a ventilation issues.


  • Gurgling
    • If you hear gurgling come from your drains you likely have poor drainage caused by ventilation issues.


  • Foul Odors
    • Foul odor can be another sign of poor drainage or ventilation issues.

Water Heater Odors

Note: Not all foul odors are caused by venting problems. Foul water odor could be coming from your water heater.

  • Missing Water in your Toilet
    • Nope, the dog probably isn’t drinking all the toilet water! (Source) If you find your toilet is missing its water you may have either a drainage leak or a ventilation problem.


  • Air Bubbles in Your Toilet Water
    • Seeing or hearing bubbles rise from the toilet bowl is another sign that your drainage system isn’t getting enough ventilation.

All of these issues can be caused when your drainage system is air-locked or when the p-traps are emptied of their water due to poor ventilation. Learn more about drainage noises here. 

If your drain lines leak you’ll probably be able to tell. Water or dampness under your home is a big clue but foul odors and soggy ground can also be signs. Repairing a drainage line leak is fairly straight forward – you find the issue and replace that area. However,  if you have determined there is no leak but you are still incurring issues described above you likely have a ventilation problem.

Venting Your Drainage Lines

A healthy plumbing system must be able to breath.

Think of a drain system as having two elements within the same pipe. The lower part of the pipe is where the waste water goes and the upper part is how the ventilation enters to provide the lower drain lines with proper (neutral) air pressure.

A two liter bottle may help explain this better:

When pouring soda out of a plastic 2 liter bottle you can see just how important ventilation can be. Turn the bottle completely up, where no air can enter the through opening, and the soda gurgles and slows. If you don’t turn the bottle completely up and allow air to enter the soda comes out faster and more smoothly. That’s exactly what proper ventilation does for you drain lines.

Inspectapedia.com explains the functions of plumbing vents well:

How do Plumbing Vents Work & Why Are they Needed

The venting system equalizes the air pressure throughout the waste piping system. Why does this matter? Let’s look at four functions of vents.

1. The waste won’t flow properly if it can’t push the air in the pipe ahead of the waste out of the way. Plumbing vents allow air out of the waste pipes.

2. The waste won’t flow well if it’s held back by low air pressure or a vacuum in the pipe behind it. Vents allow air into the waste pipes.

3. We don’t want the water to be siphoned out of the trap every time a fixture is used. It’s the water sitting in a plumbing trap that stops sewer gases getting into the home. Vents allow air in to prevent a siphon.

4. Plumbing vents allow sewer odors to escape from the house, venting safely above the roof. Without venting, the sewer gases seep through the water in the trap and enter the house. Vents help sewer gases escape outdoors.

Allow building drains to flow freely by allowing air into the drain system, avoiding the vacuum and slow drainage that would otherwise occur at fixtures.

Allow sewer gases to be vented safely outdoors. Because sewer gases may flow back up into the building drain piping from a public sewer or private septic system, and because some sewer gases are included in building waste flowing through the piping, the plumbing vent system needs to carry these gases outside, usually above the building roof, where they are disposed-of safely and without leaving unpleasant, or possibly dangerous smells and gases inside the building.

Ventilation can be achieved in two ways: through proper use of vent stacks and through auto vents. In cases where a pipe can’t have its own venting, plumbers use a product called an auto vent, or air admittance valve.

Plumbing, Drainage, and Ventilation Terms

Plumbers, like all construction workers, speak a different language from the rest of the world.  Living with a master plumber for 18 years has given me just enough time to learn some of their language (not all of it by any means). Here are some of the more common plumbing words and their meaning:

Wet Vents

Wet vents are a drain system where one pipe serves as a vent for one fixture and a drain for another (source) or a waste pipe that also serves as a vent pipe (source).

Wet vents can consist of a toilet and sink (left image below) or a toilet, sink, and tub (right image below). It could also be the kitchen sink and the laundry sink, whichever is closest. Here’s how HomeTips.com explain wet vents:

With wet venting, fixtures that are relatively close to the soil stack (the main vertical drain-waste-vent pipe) are connected directly to it, even if the section of stack above the connection serves as a drain for another fixture.

wet vent example - toilet and sink
wet vent example - toilet- sink-tub

Stack Vents

A vent stack is the small pipe that you see coming out of your roof. It completes the wet vent system.

Regular Checkups of your Vent Stack 

Vent stacks can get clogged by leaves, birds, rodents, and countless other things. They can also settle, either due to poor installation or accidental cutting. Luckily, you can buy toppers that allow good air flow but keeps things from falling into the pipes. Vents can also get crushed or bent so a regular checkup is recommended to ensure there are no leaks around the seal and that nothing is blocking air flow.


repairing a plumbing vent stack

Inspectapedia.com has a couple of great pages about stack repair:

Plumbing Vent Repair 

Plumbing Vent Code Problems



Air Admittance Valves

You’ve likely never noticed an air admittance valve, or auto vent as some call it, under your sinks or inside your walls. Even if you have seen them, you probably didn’t realize how important it was to your home’s plumbing system. They are handy little things!

An air admittance valve is used in cases where connecting a drain pipe to a stack vent is difficult or impossible. They ensure that waste goes down to the sewer and gases stay out of your home.

Look under your sinks and see if you see something like this (it could be black or white, straight or domed):

 Cheap air admittance valves


How do Air Admittance Valves Work?

DIYAdvice.com explains AAV’s best:

Air admittance valves are operated by gravity. When water and waste move down a drain line, it creates negative air pressure in the pipe. This negative pressure lifts the sealing washer and lets air in, which allows the waste to drain away freely. When the negative pressure ceases, the sealing washer falls back in place. Earlier versions of this device were spring-operated. Such units are still available but are not reliable and don’t meet code in most places.

how an air admittance valve works

Essentially, an air admittance valve acts like a set of lungs for a weakly ventilated drainage system. It allows the pipe to suck in air when needed and yet closes off when it’s not needed.

installing an air admittance valve under a sink




Studor Air Admittance Valves

Studor is most plumber’s favorite brand for auto vents, or air admittance valves. Joe, the master plumber of the family, always recommends that homeowners replace their original manufactured home’s generic air admittance valve with a Studor brand as soon as you notice signs of failure. These valves do fail and there is a huge difference between a $5 item and a $35 item.

(Note: Studor does not pay us for this recommendation. After 18 years as a master plumber you tend to learn what works and what doesn’t.)

This video from Studor explains how their air admittance valves work:


How to Install an Air Admittance Valve Under Your Sink

If you notice any of the above signs of drainage or ventilation issues you may want to install or replace an air admittance valve.  DIYAdvice uses the following images and descriptions in their step-by-step guide on how to install an air admittance valve under a sink:

 installing an AAV onto a drain pipe - step 1

Step 1

Install the PVC drain line, the sanitary tee, and the P-trap for sink. The appropriate coupling for the AAV (glued or threaded) attaches to the tee. Check the manufacturer’s instructions and local codes to determine the proper height for the AAV above the drain (source).

installing an AAV onto a drain pipe - step 2

Step 2

Depending on the type of fitting, glue or screw the AAV in place.

installing an AAV onto a drain pipe - step 3

Step 3

Depending on local codes and the AAV model, the completed installation should look something like this (source).

Other Drain Pipe Questions and Answers

Question 1:

I live in a 1987 mobile home. When the washer drains, water will back up into the kitchen sink and the fumes are horrible. Sometimes the water even overflows from the drain onto the laundry room floor. I see no vent stack thru the roof nor do I see any under sink venting devices. What do you suggest to correct this problem?


Answer: You are experiencing a very common issue in manufactured homes. It’s kind of a double whammy of not enough (or failed) ventilation and possibly too small of a drain line from the washer.

First, try adding a Studor auto vent under the kitchen sink. That should help the smell. Studor is the best name brand and well worth spending the extra money over the other auto vents.

If your washer drain line is only an inch and a half pipe you may want to consider re-piping it with a two inch pipe. While doing that, tie it in under the house directly to the main drain/trunk line itself, separate from the kitchen drain. That will definitely fix your problem! Those 1.5″ pipes just aren’t meant to handle a lot of water, especially high pressure water being released from a newer washer.

Try the auto vent first, especially if there is no stack connected to the immediate system (though there could be one in the walls that has failed – the cheaper vents seem to fail after only a few years).



Question 2:

I have a 1981 Hallmark 2 bedroom trailer. Our bathroom and kitchen sink won’t drain. The tub and toilet are fine. I’ve taken apart the plumbing under the sinks, and ran a snake as far as i could, and still nothing. I’ve crawled all under the trailer, and the only lines I see coming down and connecting to the waste/septic is for the washer (also fine). The trailer is insulated very well underneath, and i’ve cut a couple spots looking for pipes under the sinks but for the life of me I can’t find anything lol. I’ve even googled various phrases relating to the plumbing plan, to no avail. Any ideas?


Answer: Its most likely a blockage or ventilation issues. Try a true professional plumber’s snake (those they sell at Lowe’s or Home Depot are not that great and are mostly for sinks, not drainage line blockages. You should be able to rent one. Poor ventilation could be air locking the system as well. Those are the most likely issues.




 Question 3: 

I have running water, but I have this horrible stench in the kitchen and it sounds like scratching in my walls first it was on the repair side of the house now alternate on both sides. The odor became so bad 4 days after we had water we left the house after raising 5 windows in the house. I returned the odor comes and goes and I haven’t heard the scratching noises. Please help. Asap



It sounds like you have an open sewer pipe or a ventilation issue. When you had your dishwasher uninstalled did the drain to the dishwasher get capped too? Maybe the dishwasher’s drain was accidentally left open. All you’ll need to do is find that and cap it like you did the water lines.

If its not an open waste line from the dishwasher, then it’s possibly a ventilation issue. The noise could be your pipes and that usually means the system isn’t able to breathe properly. You can either look for a broken vent line (poor glue jobs, settling, or accidental cutting are the usual culprits when it comes to disconnected ventilation lines) or you can try installing an under-the-sink Studor vent. It will act as a mini-vent and help rid your home of the odor.

My money is on the dishwasher drain assuming you had none of these issues until the dishwasher was disconnected.


Ask Your Own Plumbing Questions Below

To be honest, it’s difficult to explain such a complex issue as plumbing. It’s one of those cases where you can give too much information and too little very easily. If I haven’t made something clear please feel free to let me know!

If you have any plumbing issues feel free to ask questions in the comments below. I always forward your questions to a licensed master plumber with 18 years experience – he knows his plumbing (the hard part is putting his knowledge into the right words). On our first plumbing article we were able to help answer over 60 homeowners with their plumbing questions – maybe we can help you too! Click here to read them.

Thank you so much for reading Mobile and Manufactured Home Living! 

51 Responses

  1. Paula Hunter

    I’m hoping you can help direct us in the right direction. We live in a 1996 manufactured home. When the wash cycle goes to rinse, the kitchen sink gurgles and we have a sewer smell. We had the septic pumped and they checked the outside lines and said all was good on their end. We had a plumber come in and replace the vent under the kitchen sink and also the vent in the wall by the washer and snaked the pipe near the washer. It did not correct the problem, still gurgling and sewer smell. I really do not know what to do next or what to tell the next plumber to investigate. I really don’t want to keep spending money and not fixing the problem. I hope you can help with suggestions, etc… Thanks.

    • Crystal Adkins

      Hi Paula,

      Hmmmm, this sounds like a ventilation issue. Since nothing else has worked, try cutting and capping the original washer line and then running a new washer drain line and tying it into the trunk waste line under the house further downstream than where the kitchen lines are attached. This will allow the system to get the right ventilation route and allow the auto vent under the kitchen sink to be able to work like it should (inhale instead of trying to exhale). Also, most manufactured homes should have a vent going out of the roof for the washing machine (especially if it’s grouped close to the kitchen) instead of an auto vent in the wall. I’m not sure why yours doesn’t have it.

      Hope that helps! Let me know how it goes!

  2. Felicia Grant

    My family and i lves in a double wide manufacture home since 1996. Ever since my dad past away 8 yrs ago the house has been having some terrible issues, such as the plumbing. Underneathe the house one of the pipes has come loose and everything s running straight down into the ground, toilet does not flush completely, you can gear water running right now. The smell is horrible, we have to wait days at a time just to use the washer. Please help, my mom is a double amputee, senior citizen, and widower on a fixed income.

    • Crystal Adkins

      Hi Felicia,

      You need to get under that house and fix those pipes somehow. Churches and local charity organizations will sometimes help you work on the home, especially if human waste is just going on the ground (that’s really bad for the environment and for everyone living there).

      Pipe isn’t that expensive thankfully.

  3. Leslie

    Hi, my kitchen sink is clogged. I have checked all pipes under the sink and no blockage is there. I went to the store and bought a snake. I snaked it at least 15 times, nothing was found on the tip of the snake and clog was still there. I have done the baking soda and vinager, plunger and chemicals. So far no luck, and thoughts into where I need to check on a double wide?

    • Crystal Adkins

      Hi Leslie,

      Sorry it took so long to reply but I was waiting on my master plumber friends to reply. Here’s what he says:

      “Sounds like it’s a grease clog in the kitchen line underneath.. a snake will go through grease then close back off. Bout need to blow it out either with drain king on end of hose (this kinda takes knowing what to do)… or cutting line underneath that goes to the kitchen and or clean or replace.”

      Best of luck – let me know how it goes!

      • jessica artz

        e had the same problem last week. We used drain liquid and a snake and finally got free. Now my hubby went under the house to make sure we didnt have a leak etc. There is NO water under the house,but there is a huge bubbled out part the plastic lining and full of water! My hubby had us turn all the water in the house on while he was under there and no NEW water is going into this bubble,so that tells us that unblocking the clog is letting the water flow the way it should. My question is,s that water from having the block? Is there an overflow that allowed it to fill up? and how should we go about emptying it ourselves?

  4. Laura

    We just installed a new toilet and it was working fine for about 5 flushes. We then unhooked and installed a new sink. Unfortunately our supply lines and drain were too short and we left it all until I could go back to the store. The next morning it flushed right the 1st time, but then started having a very weak flush, slow drain, and gurgling. We have the sink hooked up now, and installed a new vent under the sink. Of course, we’ve plunged it several times, just in case, but no luck. Our mobile home is 17yrs old. Is there anything else we can do? Thanks

    • Crystal Adkins

      Hi Laura,

      The drain probably dropped when you unhooked it for the sink which caused it to hold water underneath and cut the vent off to the toilet. The drain underneath is basically just a p trap so look under the toilet and make sure that waste pipe is well-attached and that the trap is holding water.

      Best of luck!

  5. Jeanette Hammons

    I need HELP. I’m 79 and husband is 86, unable to do repairs so I’m healthy as a horse
    and I crawl around under our doublewide if a problem happens. Here’s my problem.
    In Jan 2016 I paid someone to change my shower drain (bathroom #1)and washing machine to drain out in my yard. (we live way out in the country). All of a sudden the washer water drain is backing up in my commode and also in the 2nd bathroom tub. Along with commode waste. I find the washer drain tee’s into a vertical line going toward the outside drain but also toward the septic line. Do you have any idea what I need to do.

    • Crystal Adkins

      Hi Jeanette,

      It sounds like your sewer trunk is clogged a little and is causing the stuff to backup and toilet trash to come up into the shower. You may want to cut and cap where the washer water goes to sewer line.

      Best of luck!

  6. james safari mwamure

    hi thanks for the knowledge you provide to people.its amazing. i would like to know if you have lessons and certificate courses which one can take for free and online

    • Crystal Adkins

      Hi James!

      Thanks for the kind words. I don’t offer anything but I’m happy to answer questions via comments. It may take me a few days but I get to them eventually!


  7. Sue Durst

    I hardly ever do this but felt compelled to write this time. Your website is well organized and well written, especially since you aren’t a master plumber yourself. (my heart sunk when I read your post about not being a team anymore, I am sorry) Regardless, I can tell the website is/was your baby and I bet you wrote most of the extremely informative, easy to understand articles yourself (of course, based upon information provided by the master plumber). I noticed the last Q & A was early 2016 so I am thinking your heart is not in it anymore :( I just want you to know that I have used the information you provided many times for various mobile home issues/projects with great success and your efforts (and master plumbers expertise too), are greatly appreciated.

    If you don’t want to continue with this site, I highly recommend doing another website of your choosing. You have a way with words :)

    • Sue Durst

      Oops i guess your site is updated, my apologies. But my point is…thank you so much for all you do!

    • Crystal Adkins

      Thank you for the kind words, Sue!

      Admittedly, after 5.5 years of blogging, and over 500 articles about mobile and manufactured homes, I do have to put in a little extra effort to get motivated to write new articles! Apparently, that is common for bloggers after many years.

      I still love the homes and the people in them, though! My 1978 single wide completely changed my life for the better and I’ll forever be thankful.

      I try to publish 2 articles per week but sometimes life gets in the way. While I can’t really provide plumbing help any longer (outside my comfort range), I can at least try to point people in the right direction and I’m happy to do that.

      It was a good run while it lasted! Thanks so much for the kind words!

  8. amber

    Hello, I live in a 2008 mobile home, and I am hearing thumping in the walls, slow drainage in the sinks, bubbling in the toilet when the washer drains. Am I having a ventilation issue? What am I looking for when I go up on the roof to check the stack? Also on the back of my home is an odd spigot, it has a seal on top and it will not turn on? I think it might be pressurized? Is it necessary or can I replace it?

    • Crystal Adkins

      Hi Amber,

      I would check the waste lines first. Make sure there is nothing blocking or partially blocking the drainage lines. Snake out each point that you are experiencing issues. After that, I would check the washer drain pipe. If it is too small it can’t get the proper air flow. New washers are especially powerful so make sure to have the right size drain line that the manufacturer recommends. A quarter inch can make all the difference.

      If that doesn’t fix it then check the ventilation lines. You will want to make sure there is nothing blocking the pipe sticking out of your roof (birds, etc). You can snake it out (snakes are available at Lowe’s for $25 but they aren’t very good – if you can rent a professional snake or borrow one do it). If there isn’t blockage you’ll likely want to hire a professional (or maybe try an auto vent).

      PS: Make sure that all professional plumbers, electricians, contractors, etc. you hire have taken the exam for their respective licensing (journeyman, master, apprentice) and was not grandfathered in.

      Best of luck!

  9. Joel

    Hi Crystal, thanks for sharing this. I smell a foul odor on the drainage since last week. It is not clogged yet it really smells bad?

  10. Rita

    When I flush my sons toilet it backs up into the bathtub. The only way I could get it to drain was to open the main pipe line? Is there a ventilation issue

    • Crystal Adkins

      Hi Rita,

      It’s more likely to be a stoppage in the waste line than a ventilation problem. If you aren’t dealing with noise, smell, or other issues it’s probably just a clog. Best of luck!

  11. JoNell

    Me and my hubby are new to this we just purchased a 1996 single wide home with 2 bed 2 bath and just today the whole plumbing seemed to work fine until I washed the dishes. Never had a issue with drainage till now- the water wouldn’t go down in the sink I removed the drain stopper from the sink I was washing dishes in and neither water to go down we cleaned out the pipe but still having issues…just trying to find some answers

  12. Kiani

    We just installed a brand new sprayer for our kitchen sink and now about a month later the water coming from it stinks like a grease trap! The old sprayer never had this issue and nothing in the plumbing has changed. The smell does go away after running it for a few minutes but if you let it sit again for about 20 minutes the stink is back. The smell hasn’t affected any other faucets… I do know that the smell is horrible and whatever it is in the water almost killed one of my plants… Help please! Oh and PS…. I’m on well water. Thank you!

  13. Lauren

    Hello Crystal,

    Thank you so much for answering perplexing plumbing problems! I’m a “do it yourself” if at all possible person. I recently purchased a single wide with one bathroom. The tub faucet in that one bathroom makes a “banging” problem when I shower. It happens when I fill the tub with water to take a bath as well. If I turn on the hot water full blast, it does not “bang”. I found the access panel to this tub inside a closet. Do I need to pull the access panel and do something in there?

    Thanks again, Lauren

  14. Kevin Ashley

    Hello. We bought our 1993 16X80 mobile home about 8 years ago and county code requires a treatment plant and septic tank that is pumped out to 3 sprinklers behind the house. My problem started about a year ago with water backing up into the masterbathrooms sink and tub and separate shower drains. And the toilet wouldn’t flush. I called a friend who helped install the main line under the house, he snaked it and everything was fine–for a while that is. Then we installed new toilets in both bathrooms and the master bathroom was only area that started gurgling and water rising up into tub and shower. I’ve checked the stack vents and sink vent(AAV). To no avail…please help. Any pointers will be appreciated. Thanks and God Bless

    • Crystal Adkins

      Hi Kevin,

      This could be a couple different things. If it is ventilation try adding an additional vent for the master bath sink, tub, and toilet (tie them together on a single waste line). If it’s a grade issue on the waste line you’ll want to get it the T branched and graded properly (I’ve even seen toilets need to be raised on a platform to get the right grade).

      It’s so tricky to try to give advice online. I’d def look into the vent stack and the waste line grade. Sorry I can’t be more help. Best of luck!

  15. Cindi Eshelman

    I live in a 70’s mobile home. Just recently, we’ve been having problems with air bubbles coming up in the toilet when we shower, and the toilet not flushing well. I took the toilet off and had it snaked out, which seemed to fix the problem..until yesterday. One plumber I called out said the was a bow in the drainage pipe under the toilet (wanted 4000+ to replace it). We made sure the vent stack was clear (snake came back completely dry). What now? Can I replace the pipes myself?

  16. Matt W.

    We recently had to install a new sewer line connecting 12 RV sites to an existing sewer line that has 4 sites and 1 deluxe cabin (not roof vented). The cabin is the last sewer connection before the line turns, and goes 25 feet to a 2000 gallon tank. Odor complaints began after we did this (could be a coincidence) about 3 weeks ago. It is intermittent, folks check in and it’s fine then 3 hrs later it stinks. We tried to determine the exact odor, sewage, sulfur, rotten eggs, what is it, etc……….We augured the main line from cabin to tank. We put a vent coming out of the cabin in (before the drain) and up and outside of the cabin. This park model is not vented through the roof.

    Then after a rotten egg smell I thought of bacteria in the hot water heater, then water sitting in traps and causing odor there. So I throughly flushed the heater with peroxide. Odor returned.

    Spoke with my local septic guy and he said a couple things. The pee traps could be cracked, clogged (we’ve dumped plenty of Drano), or just bad. They smell when they dry out. He believes the odor is sewer.

    It may be sewer……when someone dumps, or something passes by, intermittently, there is an odor. Then gone. BUT we vented the line coming out of the cabin and drain. Maybe this should not be vented because of creating the wrong pressure. Should we vent before as well? Is it something already in the cabin piping?
    I had a galstay in the cabin 2 nights ago. And let me know if an odor returns.
    It returned.
    We just aired out the cabin and replaced two Studor vents under 2 sinks. Is there one in the shower? We will close it up later and continually check later today, etc…..
    I’m now thinking the upward vent we attached to the drain line outside the cabin is creating a pressure problem inside. Or there is a Studor vent under the shower we missed.
    Your help is greatly appreciated

  17. Veronica

    I have a double wide mobile home and we have noticed leaking at the p trap. We replaced the washer and it still leaks. I have a bucket under it to catch the leak. Yesterday I noticed that the underside of all the kitchen cabinet fascia are warped and seemed damp. I noticed that when putting the p trap back on you have to lift the drain pipe that runs through the floor because there is a gap where the p trap connects. The pipe that connects through the cabinet floor appears to lift up out of the floor when we lift it to attach the p trap. Is it possible that the straight pipe going through the floor of the cabinet is not connected properly and causing it to leak under the cabinets? How hard would that straight pipe be to fix?

  18. Jim

    I have a 1999 double wide with a 40gal electric water heater. I cool to warm water coming to my faucets (all brand new) and no hot water.
    Also, the WH hot side gets hot to the touch and the cold side gets warm but still only warm water at the taps. If i release the Pressure valve the hot side of the tank gets hotter for a few minutes then it turn cool. I am thinking there is a 3way valve somewhere underneath the home, but i can’t seem to locate it. Any ideas?

    • Crystal Adkins

      Hi Jim,

      Unfortunately, this is one of those issues where it would be near impossible to answer without looking at it. Have you checked your elements to make sure they are working properly? If so, you’ll want to make sure you’re water lines aren’t crossed and your wiring and amps are the right size. Other than that, it would be hard for me to guess what else it could be.

      Best of luck, let me know how you end up fixing it!

  19. Ilene Reff

    I am interested in purchasing a new park model and would like to transfer the 40 gal water heater from the one I have now the heater will be placed into a dedicated closet and due to a loft above I am not able to vent through the roof can it be vented through a sidewall.

    • Crystal Adkins

      Hi Ilene,

      The answer is going to depend on your location so I can’t give you an exact answer. I can say that you usually can vent off a sidewall as long as it’s an exterior wall and the distance is minimal (a few inches). Vents can get pretty warm from a water heater.

      You’ll need to call a plumber to make sure you’re within regulations. Best of luck!

  20. Justin L.

    Hi, me and my fiance are new to the whole home living, we invested in a 2004 Fortune double wide home, it has two bathrooms, a master and the guest. Right now we are dealing with some issues, the other day I took a shower and we did the dishes and every thing was fine, great drainage and nothing out of the ordinary. However my fiance did a load of laundry and when it when into its spin/drain cycle all that water started coming up into both tubs! Leaving about 2-3 inches of water in them and you could tell it was dirty laundry water, they didn’t drain at all for almost 10 hours. The water in the toilets is also gone, I took the lid off of the toilet and let some water into the toilet bowl and as that water went into the toilet bowl you could see the water rising inside the tub. The kitchen sink however doesn’t seem to be affected or to affect anything at all. I have searched and searched for answers and so far i can’t find a solid answer! I wouldn’t think it could be a clog because the community we live in just had our main line snaked out professionally. We’ve only been living here for about 2 months and it’s very depressing and over whelming.

    • Crystal Adkins

      Hi Justin,

      It sounds like you have a stoppage that has also cut your ventilation off. This would make the drains slow and since you aren’t getting the pressure equalized the water in your traps is pulling up into your toilets. You’ll need to find where the clog is and snake it out.

      Best of luck! Let me know how it goes!

  21. john geffeert

    we have a sewer smell in our bathroom and bedroom. checked ventilation pipe that extends through roof. Can a ventilation pipe have an L-shaped pipe that extends through roof. I put a wire down pipe and hit something hard about 12 to 18 inches down.

    • Crystal Adkins

      Hi John,

      yes, your vent stack will usually include horizontal pipes. If you have a stoppage you’ll definitely want to get that cleared, that’s probably your problem. The system has to be able to breathe. Best of luck!

  22. Laura

    Please tell me where to find an outside water source for a 1988 Deam. I know where the pipe comes in for the water heater,etc, but can not find any pipes to hook up a water hose.

    • Crystal Adkins

      Hi Laura,

      The water hose bib or connection is usually near the back door, closer to the corner (while it will be close to the water heater it usually isn’t in the same ‘line’). It may be hidden 6″ or so back from the skirting (to keep if from freezing) so you will need to look fairly closely to find it and hopefully the skirting will have an access panel or door there. If the home doesn’t have a connection you should be able to install one where the main water line is going into the home.

      Best of luck!

  23. Bill

    I’m in a bath and a half single wide. Had an issue with smelly hot water a year or so ago, flushed the water heater and that took care of the issue. the main bath, and kitchen the water is fine. The half bath, the hot water stinks. That room isn’t used as much, it clears if you let the hot water run (takes a while to get hot since it is at the far end of the trailer) So I suspect its from the water sitting in the supply line. Is there anything I can do short of replacing that supply line?

    • Crystal Adkins

      HI Bill,

      Sounds like your water is just stagnating in the line since it isn’t getting used much in that room. I don’t think new lines will help in this situation – it’s likely the water more than the pipe but you may be able to solve the issue (if it bothers you a whole lot) with a re-circulating system. A pump with a built-in timer is installed on your water heater that opens the loop when the hot water in your line cools and recirculates into the heater to re-heat. It would keep the water fresher and likely take care of that smell for you. If I recall correctly, a re-circulating system is around $200 (it’s liked because it helps save water by having hot water on the ready).

      Thanks so much! Good luck!

      • Doug

        I’m thinking maybe it’s just easier, and less expensive, to just turn on the water, flush the toilet, in that bathroom once a week!
        Re-circulating pumps aren’t too expensive. But, then, there’s the cost to put it in. And, then, the water heater runs so much more to keep that water hot all the time.

  24. Leah G

    We are having a sewage odor problem that comes and goes. It’s worse in the laundry room and the air conditioner unit is also located there, so the smell gets distributed all over the house. We have a brand new septic system (only 1 year old) and only the kitchen and the toilets drain to the septic system. Everything else drains to the backyard as grey water. There is no odor where the grey 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! The plumber has come back out, but we are still getting the smell. Any ideas?

    • Crystal Adkins

      Hi Leah,

      Sounds like you have a pipe loose in your vent stack. Inspect the ventilation pipe to ensure it hasn’t separated (you may be able to find a plumber with a fancy camera that can run through the pipe to find the issue so you don’t have to cut a hole or remove the wall). Your plumber may be able to install auto vents at the kitchen and bathrooms too. You want to make sure the connections are tight to the septic tank too, settling or tree roots can cause damage very quickly.

      Best of luck, let me know how it goes!

  25. Jeni

    Thank you Crystal for this very informative article! I had some issues I had questions about and found answers here. Thanks so much!

  26. Suzanne Melton

    Great article, Crystal…it’s almost as if you have a close, personal friend who is a plumber!

    The article doesn’t mention whole-house water filters but, if anyone reading this is considering have one installed, don’t forget to change the filters every six months (April 5 and October 5 here).

    If the filters aren’t changed, they will eventually “explode” and tiny little carbon particles will travel all though the system.

    • Crystal Adkins

      Hi Suzanne!

      I may know one or two plumbers…lol…Thanks so much for the tip! I’ll put filtration systems on my t-write list! Always good to hear from you!


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