Why Does My RV Smell Like a Sewer?

Why does my RV smell like a sewer?  If you bought a used RV and everything seems to be going well until you walk into your RV and there it is that horrible sewer smell. Which is the stinky smell of hydrogen sulfide effusing from your black tank which knocks you out each time you get into your RV? By the way, this can also happen in New RV’s.

Why Does My RV Smell Like a Sewer

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Having dealt with this personally after buying a used fifth wheel. We have only been RVing a couple of months when we started smelling a sewer odor in the bathroom. We called our dealership for advise, below are instructions they gave us. Our problem ended up being a broken seal on the flap inside the toilet bowl. Our toilet bowl wasn’t holding water.

Top 3 Causes of RV Sewer Odor:

  • A Leak in your hoses or tank
  • Toilet flapper seal needs replaced
  • Your tank needs emptied or cleaned

Note* – Always refer to your RV’s owners manual for instructions before attempting any repair.

How to get rid of Sewer Smell:

It happens to everyone at some point. This guide will provide you the information needed to help eliminate this odor in your RV.

To get started,

  • Check your hoses and tanks for leaks.
  • Make sure you don’t have any leaks at base of toilet
  • Do you have any clogged drains?
  • Does your toilet hold water?
  • Be sure flapper in toilet bowl closes tightly, if not try cleaning with soft rag.

Start with flushing your black tank:

Why Does My RV Smell Like a Sewer

  • Now you need to drain the black tank and then the grey tank water. The key to keeping your sewer hose clean and not smelly is to drain the black tank first before draining the grey tank. This is because, the grey water will flush out all the mucky muck from the black tank.
  • One mistake some RVers make is to keep their grey tank completely open when they are connected to the sewer. By doing this you won’t have pressure from the water in the grey tank to flush out the mucky slime left by the black tank.
  • Once you completely drain your black and grey tank, close back up tightly. And now that your black tank and grey tanks are closed, you can go back inside the rig.

Why Does My RV Smell Like a Sewer

  • Once back inside, take a look at your system monitor, and when it indicates a green light, then it means you’ve completely drained your tanks. You can now head to your bathroom for the next step.
  • Back in the bathroom, make sure to flush the toilet a couple of times, to put a base level of water in the tank. This is because you wouldn’t want the tank to be dry when using the softener, you will be using for this process.

So, lift up the lid of your toilet and flush for the first time, and allow the water to come up to about 3/4 of the way within the toilet itself, and then flush it again. And when a good amount of water is back up, close it up so that the bottom is sealed, when done you can fill the toilet up.

Why Does My RV Smell Like A Sewer

  • When you have about two thirds of water in your black tank, the first step is to add some water softener to your bowl filled which should be about half full. For areas like Arizona, the problem of hard water makes it easier for solids to stick to the sides of your black tank. This is what causes the stink problem.
  • Pick up any water softener of your choice (the cheap stuff will work too), and then directly add a about 2 cups to your toilet bowl, with the toilet brush (gently, as to not disturb the seal), stir around the tank for 2 to 3 minutes and then flush it, and then flush it again with another toilet bowl full of water. This will ensure that there is enough of the softener to work in the black tank. While stirring the water it will also clean the toilet bowl too.

Why Does My RV Smell Like A Sewer

  • Now at this point, you just have clean fresh water straight from the city water source. Fill your bowl again, add some liquid soap to your toilet bowl. This will help clean the black tank, and sanitize it a bit, as well as giving it a more pleasant smell.

Once you’ve added your regular liquid dish soap, stir around with the toilet brush than you did initially and then you flush. And then fill the bowl back to about 3/4th again, and then flush it down one more time and fill it back up to about one half.

Why Does My RV Smell Like a Sewer

  • You are now done with the first application. Now, when the black tank is about halfway full and the toilet bowl is ¾ full, add a couple drops (maybe 3-4 TBS, I know some will say NO! But it works for me) of Clorox bleach to the toilet bowl, and flush it down, and then flush it  again (never leave the bleach sit in the toilet bowl or black tank as it could damage the seals, hoses or tank) with fresh water. Empty black tank again to remove the bleach and flush with clean water.  This will help with the odor and disinfect the tank and make sure that everything is relatively clean. This process should help you eliminate the smell.
  • CautionDo not let the beach sit in your tank, be sure to flush with clean water. Skip the bleach if not comfortable using it. Always refer to your RV’s owner manual for instructions.

Here are a couple of points to note when using this process:

First, you may not have to do this every single time you empty the black tank. However, when you buy a used RV, make sure to use this process before you use the toilet. This due to the fact that you do not know how dirty and stinky the black tank is.

Use this process every time you clean your black tank for a awhile until you’re confident the smell is gone. Also, the hotter the weather, you will want to do this more often. This is because hot weather causes materials in the black tank to ferment faster. Depending on how hard or soft the water is in your area, will also determine how often you’ll want to do a thorough cleaning.

Finally, in general, the more water you flush, the better it is in terms of smell and cleanliness. If you have a particularly heavy movement within the toilet (sorry), maybe an extra flush after will do the trick, that is if you’re hooked up to city water. So, if you have water available, then the more water you use, the better.

How to Deal With False Black Tank Sensor Reading:

  • If you see a red blinking light next to the blackwater, typically means the tank is almost full and needs to be emptied. Even though the system monitor is notoriously inaccurate, it might give you a general frame of reference regarding how full your tank might be.

If it indicates full, even though you just emptied the tank, here are a few tips to help you resolve this issue.

How this problem happens is that there are plastic tanks called ABS tanks underneath your RV, and this tank is responsible for holding our water waste. Metal sensors are spun into the sides of these tanks, and wires are hooked to the tank which goes back into the monitor panel. What happens is that there are sludges and slimes which gets stuck on the sides of the black tank, hence giving you a false reading when you empty your tank but your sensor still indicates it’s full.

Here are a couple of things you can try to fix you sensor:

  • Fill the toilet bowl with an RV toilet paper. When filling the toilet bowl with the toilet paper, fill the toilet bowl with water before going #2. Obviously, if you’re boondocking, this will be more difficult for you because you want to get the longest life span out of the tank if possible. However, if you’re at a campground with water hookup this won’t be a problem.
  • What this does is that it will fill the tank with more water, and also help solidify anything kept in conjunction with your septic cleaner. Ensure that you’re using an appropriate RV toilet paper. RV toilet paper will break down easier than ordinary household toilet paper.
  • Fill the toilet bowl up to about 3/4th the volume possible and dump it to get the tank as full  as possible, to help clean out the tank.

Another thing you can do is to purchase a sewer sprayer, and what this does is to spray your black water tank. However, new RV models do come with this sewer sprayers. If you’re in a 5th wheel, this might be tough to use because a fifth wheels tank is father from the toilet, which is not the same in other rigs.

Why Does My RV Smell Like a Sewer

Mobile Suite Fifth Wheel

If you have a really dirty or hard-to-clean sensor, what you can do is to fill up a five-gallon bucket with very warm water(not hot) adding 1 cup of softener then dump it down your empty black tank via the toilet. The warm water’s steam will help loosen any solid that might have stuck with the sensors in your tank. Repeat if needed. Always refer to your Owners Manual.

You can also try tank sensor cleaner. What you do with this is to fill up your toilet to about 3/4th full and then you flush it out to the empty black tank. You might want to allow it in the tank for 24-hours and then flush it out. Basically, what the liquid will do is soften all the solid materials in the black tank. Follow manufacturers instructions. I have not used tank sensor cleaner, but many RVers I know have had success using it.

These tips work 95% of the time, however, if they do not work for you, do visit the nearest RV dealership near you.

Checklist for keeping your RV smelling fresh:

Flush twice or more if possible (except when boondocking)

Check for leaks in tanks and hoses regularly

Keep drains clean

Never store your rv with dirty tanks

Only use RV toilet paper

Use your favorite toilet deodorizer (we use Camco TST)With the above tips, you shouldn’t have a problem with black tank smell or false sensor readings any longer.

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Happy Camping!

RV Groovin Life

Bonnie