Get Free Shipping On All Orders Over $30

Learn More

Unclogging An RV Toilet

October 11, 2019

How to unclog a plugged camper toilet RV motorhome holding tank step by step

Key Points:

  • RV toilet clogs area caused by 3 main issues: Pyramid plugs, compacted holding tanks, and misreading sensors.
  • Diagnosing which clog you are dealing with is crucial in solving your problem.
  • There are easy fixes for all 3 types of RV toilet clogs

Nothing kills RVing fun like a disgusting, clogged RV toilet! Let's be honest: isn't a comfortable bathroom experience one of the main reasons why we buy RVs? There are a number of reasons your toilet might be clogged or appear clogged and in this article we are going to discuss the causes of toilet clogs, determining which issue is causing your clog, and some easy fixes to get your toilet back in tip top shape. 


Types Of RV Toilet Clogs


Pyramid Plugs

The majority of clogged RV toilets come from pyramid plugs. A pyramid plug is literally a pile of poop and toilet paper that has built up from the bottom of your black water holding tank and formed a pyramid of waste that has now reached up to your toilet itself and is clogging it up. The formation of a pyramid plug actually comes from commonly held, but incorrect waste practices. A pyramid plug is created when you keep your black water valve in the open position during normal operation which you shouldn’t. The reason you don’t want to keep that valve open is because every time you use the toilet, the liquid waste flows freely out of the tank and into the sewer. But because your black water holding tank is flat on the bottom, the solid waste accumulates on the bottom as the liquid flows out. Over time, if you keep adding more and more of that solid waste, you will begin to build a pyramid plug. These pyramid plugs are some of the most common causes of RV toilet clogs


Compacted Tanks

A compacted tank is less common than a pyramid plug but no less frustrating. There are a couple ways that a compacted tank could develop.

The first way a compacted tank might develop is if solid waste or toilet paper clogs your discharge line (the line leading from your black tank out of your RV), your discharge port, or the tank drain. If these lines are blocked, the waste has no escape from your tank, so it builds up on the bottom of your tank. 

The second reason you might have a compacted tank is because your tank didn’t get dumped before putting it in storage. If you put your RV into storage without first dumping your tanks, all the water inside the tank evaporates, leaving the hard, dried solids behind. This will clog your discharge line and the waste trapped inside will become extremely solid, leading to a clogged RV toilet.


Misreading Sensors

Misreading black water holding tank sensors are a common problem for RVers, and many accidentally mistake them for a clogged tank.

Misreading tank sensors in your black tank are caused by feces and toilet paper coating the surface of your sensor probes. When poop and toilet paper cake onto the surface of your sensors it causes those sensors to read “full” when your tank is actually empty or only partially filled.

Note: Misreading sensors are not just limited to black tanks. They can develop in gray tanks as well. (Read our article on restoring gray tank sensors here)


Diagnosing The Cause Of Your Clogged RV Toilet

To determine which clog type you’re dealing with, here’s what to do:

  • Try opening your black tank valve. If nothing comes out, your tank is either empty, or you have a plug. If this is the case, you can rule out misreading sensors. 
  • Try to add water to your black tank through your toilet. If you can add water, then you do not have a pyramid plug.
  • If you can add water to your tank, but nothing comes out when you open your black tank valve, then you have a compacted tank. A compacted tank prevents added water from exiting the system, but it doesn’t prevent it from being added. 
  • If you can’t add water to your tank then you have a pyramid plug. A pyramid plug blocks you from adding any water to your tank through the toilet. 
  • Finally, if you can add water to your tank and water comes out when you open your black tank valve, then you do not have a clog at all. In this case, your sensors are misreading and need to be cleaned (see below).

Fixing A Clogged RV Toilet

Now that we’ve discussed the types of clogs and how to diagnose them, let’s talk about the easy solutions for clearing up clogged RV toilets. 


Pyramid Plug

If you have a pyramid plug, you won’t be able to add much if any water to your tank through the toilet (because it’s clogged with poop!). All the same, some liquid will often get through even if it’s only a tiny bit. So, before you try anything else, we recommend that you open the toilet valve and pour 1 entire bottle of Unique Tank Cleaner into your RV toilet bowl. Because this product is a liquid it will likely seep through the top of the pyramid plug and open a channel into your tank. Once you’ve been successful in creating that channel, proceed to pour as much water into the tank as you can. (Remember to keep your black tank valve closed, otherwise this water will all flow out again!) 

Unfortunately, the pyramid plug is so stubborn that the recommendations above won’t cut it. If this is the case in your situation, we recommend going down to the hardware store and purchasing some PEX pipe. PEX pipe is more flexible than PVC, which will allow you to access areas that you wouldn’t be able to access with a pipe that won’t bend. 

Use the flexible PEX pipe to break up the top of the pyramid plug, creating enough space to get water into the tank. When using the PEX pipe, first be sure to turn off your fresh water supply valve. This will allow you to hold your toilet flush pedal down and keep the valve open without filling your toilet with water. With your toilet valve open, send your length of PEX piping down the toilet and into the tank. Try to knock out some of the pyramid plug with the PEX pipe to create enough space to get some Tank Cleaner and water into the tank. 

Once you create enough space to add liquid, pour 1 entire bottle of Tank Cleaner into your tank through your toilet then add as much water as possible. Let the product work for as long as you can. There is no time that is too long for Tank Cleaner to do its job. It won’t harm your tank, and the longer you give it, the more it will digest the waste making up your pyramid plug. 

Note: If your tank is so full that you cannot add any more water, you can skip adding water to the tank. However, you should know that for Unique Tank Cleaner to work properly, it needs liquid to support the active bacteria cultures that digest the waste. So, getting as much water in the tank as possible is incredibly beneficial.

Once the Tank Cleaner has done its job, open your black tank valve and dump your tank. If you have a tank rinser or flusher, you should rinse your tank for 20-30 minutes. It’s important to run your tank rinser for 20 minutes or more after the tank contents have been broken up and successfully dumped from your black water tank. And don’t let the clear water that empties out at the beginning fool you, it often takes quite a few minutes before the feces and other waste break free and start to flow out of the tank.  

Once you’re done rinsing, close your black tank valve and keep it closed when using your black water holding tank so you don’t get another pyramid plug. It’s good practice to always keep your black water holding tank closed unless you’re dumping your tank.  


Compacted Tank

A compacted tank is a little easier to fix because your toilet opening isn’t blocked, so it’s easy to add water and Tank Cleaner to your black tank.

The first step in fixing a compacted tank is to close your black tank valve and fill your tank with water. Next, pour 1 entire bottle of Tank Cleaner into the tank through your toilet. Let it sit for as long as possible. Open your black tank and allow the tank to empty out. Flush your tank with a rinser or flusher for 20-30 minutes.

All the waste should be liquified when you open your tank, but if nothing comes out or you only get a small amount of waste to exit the tank, close the valve and let the product sit a little longer. When you’re dealing with a compacted tank, you will probably have to let Tank Cleaner work a little longer than normal. This is due to the fact that the compacted waste is so solid and, well, compacted!

Pro tip: If you’re having issues getting your tank to empty after you open your black tank valve, it can sometimes help to (very gently!) tap your discharge pipe with your shoe. This can help dislodge any chunks of waste stuck in the pipe or discharge port. Be sure not to hit the pipe too hard. You don’t want to break it! Also, using PEX pipe to dislodge chunks of waste in your discharge port or pipe might also work. 


Misreading Sensors

Like we said above, some people mistake misreading sensors for a clogged tank, but remember, if you can pour water into your tank and dump it out of your discharge port, then you don’t have a clog. In this case, you’re dealing with misreading sensors that are telling you your tank is full when in fact it isn’t. 

Our comprehensive guide to cleaning and restoring holding tank sensors will walk you through each step of restoring your black tank sensors. Keep in mind, however, that if you follow the processes given in the guide, and you still have issues, your sensors might simply be broken. If that’s the case, you’ll just need to replace them. 


Clog-Free Is The Way To Be!

We hope that this article answers all of your questions about what causes clogged RV toilets, how to diagnose your problem, and the easy solutions for unclogging those toilets. Should you still find yourself in need of help after following this guidance please don't hesitate to reach out to us! We're more than happy to help you get your toilet issues back on track!

Happy Camping!


Guide Continued Below



sign up and save. We send out frequent discounts and promotions.

Sign Up + Save

Join our newsletter and save $5 on your next order! Plus, get exclusive members-only discounts, access to our library of downloadable guides, and insider information on new products and promotions.

Learn More



Preventing Clogged RV Toilets


Pyramid Plugs

Like we mentioned earlier, your holding tank is flat on the bottom, which can cause waste to accumulate into a giant pyramid in your tank if you don’t keep your black tank valve closed. So the key to preventing pyramid plugs is to always follow rule #1 of The Unique Method: ALWAYS KEEP YOUR BLACK TANK VALVE CLOSED unless you’re dumping your tank, which we have admittedly harped on quite a bit in this article! 

But it’s a crucial point, because following The Unique Method will virtually eliminate all holding tank clogs and odors, and when it comes to pyramid plugs, keeping your black tank valve closed is the first step.

The idea is to ensure that the liquid inside your tank is a sloshy mixture. (You want it to slosh around in your tank, which will help keep the waste liquified.) You also want to make sure you’re using a high-quality, waste digesting, bacterial holding tank treatment like RV Digest-It.  All this is covered in depth in The Unique Method. The Unique Method is a series of practices that we have created through our own experience and working with thousands of RVers over the years. Try it out and tell us what you think! We've found that it can be a lot to grasp at first, but is absolutely worth it to keep your RV clog AND odor free!

You might think that a lot of people experience clogged toilets when dry camping (boondocking) because they use very little water with each flush, but in most cases, dry campers have to keep their black tank valve closed until they get to a dump station. This allows for plenty of sloshy action inside the tank that can help keep the waste liquefied, so clogs aren’t as common for dry campers as they are for full hook-up campers.

We know, we sound like a broken record, but we cannot stress it enough: keep your black tank valve closed! As much as we like to think of our RVs as our homes, the plumbing simply doesn't work the same way as the plumbing in your home, so you can't expect your waste to flow out into the sewer lines with every flush.


Compacted Tanks

To prevent a compacted tank, first make sure that your black tank valve is closed and you’re using plenty of water in your tank. In general, the more water you use, the less likely it is that you’ll experience clogs or odors.

On top of adding a lot of water to your tank, you should also be using a high quality waste digesting treatment like RV Digest-It. A waste digesting treatment will add good bacteria to your tank, which will help to break down the solid waste.

Finally, never store your RV without first dumping all the waste and flushing out your tank! This is a simple but absolutely critical point. It’s worth going through the extra effort to dump and clean your tank before you store it so that you don’t have to deal with these time-devouring and frustrating issues down the road!

And last of all, like we said above, follow The Unique Method to make sure you never have to deal with this issue again! 


Misreading Sensors

Misreading sensors can be easily restored by performing an annual deep clean of your tank using Unique Sensor Cleaner. Again, this is covered in The Unique Method as well as in our article on cleaning and restoring holding tank sensors!




Adopt The Unique Method

You bought your RV so you could enjoy life and spend time with family and friends. The last thing you want to do is waste precious time and money on fixing wastewater holding tank problems. Keeping your tanks in peak operating condition doesn’t have to be hard, confusing, or expensive if you follow our proven process: The Unique Method.

The Unique Method is a comprehensive tank care plan that we developed after years of conversations with real customers facing real problems. The Unique Method provides you with simple, preventative steps to stop odors, clogs, and sensor problems before they start so you can spend less time worrying about your holding tanks and more time enjoying the freedom and adventure of RVing. Try it yourself and see why thousands of campers trust their RVs with The Unique Method every day.

If you need more help with anything covered in this guide or simply have a comment, we’re here to help you anytime!

Contact Us




Also in Guides and Resources

What is the best RV Holding Tank Treatment? What is the better difference between rv toilet chemicals. Learn more.
Choosing The Best RV Holding Tank Treatment

November 25, 2020

There are dozens and dozens of RV holding tank treatments out there, and it can be overwhelming when it comes to knowing which one is the best for you. All of them claim to work miracles, but which treatment types are proven to work the best? 

 

Continue Reading

You Should Use Safe Products in Your RV Holding Tanks. Unique Camping + Marine
Why You Should Use Safe Products in Your RV Holding Tanks

October 07, 2020

Traditional, “old-school” RVing advice has often promoted information and RV maintenance products that are ineffective, and more importantly, can be harmful to your health. But with the advent of new research into the topic, many RVers have started to realize that a lot of the RV products on the shelves today are either really bad at their job, or even worse, dangerous. 

Continue Reading

You Need To Perform an RV Holding Tank Flush. Unique Camping + Marine
You Need To Perform an RV Holding Tank Flush

October 07, 2020

Many people may wonder, “Is a tank flush really that necessary?”. We recommend that you thoroughly flush out your black water holding tank for 20-30 minutes every 3-5 dumps. 

Continue Reading