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What Is An RV Pyramid Plug?

August 06, 2020

Learn how to solve an RV Pyramid Plug. Diagnose and fix clogged waste in your RV black tank. Unique Camping + Marine

Whether you’ve been RVing for quite some time, or you just picked up your first RV and are about to hit the road, you’ve probably heard of or experienced a little thing called an “RV toilet clog,”. Folks who have experienced a clogged holding tank often find themselves desperate to figure out how to unclog their RV toilet. Contrary to what some might suggest, clogs are not inevitable, but they can sometimes feel impossible to fix once you have one! 

The most common type of clog is a pyramid plug. The name of this little bugger is pretty descriptive; an RV pyramid plug is quite literally a pyramid of poop and paper that has built up inside your black water holding tank! We’ll get into the reason for this below, but you should know right from the get go that it’s very easy for a pyramid plug to form if you’re not following the proper RV holding tank care procedures.

In this article, we’ll be covering everything you need to know about RV pyramid plugs and how to fix and prevent them!

How to Diagnose Your Issue

Before you can do anything else, however, you have to make sure that you’re actually dealing with a pyramid plug. A pyramid plug is often mistaken for a blocked plumbing line or vice versa, which is why it’s important to figure out whether or not you actually have a pyramid plug. We’ve outlined the process to diagnose a pyramid plug below: 

  • Step #1: Open your black tank valve. If nothing comes out of your tank, you may have a pyramid plug. Close your black tank valve.
  • Step #2: Try flushing water down your toilet. If you have a pyramid plug, you won’t be able to add any water (or at least very little) to your black tank. The reason is that the pyramid of poop inside your tank has climbed up to the base of your toilet and is likely blocking your toilet line, preventing you from adding water to your tank. This could also mean you have a blocked line. 
  • Step #3: Ask yourself if you kept your black tank valve open. The truest way to know if you have a pyramid plug instead of a blocked line is whether or not you kept your black tank valve open. If you did, you most likely have a pyramid plug. A pyramid plug forms when all the water runs out of your black tank because you left your black tank valve open. If you always keep your valve closed unless you’re dumping (as The Unique Method states!), then you’re probably dealing with a blocked line between the toilet and the black tank instead of a pyramid plug.

If you believe you have a pyramid plug after completing the steps above, don’t worry! Next we’ll cover how to fix it!

After you've gone through this diagnoses, does it seem like this ISN'T your problem? Read here to diagnose if you have one of the other common tank clogs and learn how to solve it!

How to Solve An RV Pyramid Plug

Like we said above, a pyramid plug forms when all the water inside your black tank is allowed to exit the tank because the black tank valve was left open. You need a lot of water in your tank to make sure all the waste sloshes around and remains liquefied. If you have a pyramid plug, your ultimate goal should be to add as much water to the tank as possible. There are a few steps to take in order to do this:

  • Step #1: Close your black tank valve. 
  • Step #2: Pour 1 bottle of Unique Tank Cleaner into your toilet bowl and flush. You may not see anything happen at first, but after a few hours Tank Cleaner will start to chip away at the top of the poop pyramid with it’s beneficial bacteria + enzymes, and eventually it should open up enough space in the line to allow you to add water to your tank. Allow Tank Cleaner to work for a minimum of 72 hours.
  • Step #3: Try adding several gallons of water to your tank through your toilet. After you’ve allowed Tank Cleaner to work for a few hours, you will likely be able to slowly add water to your tank. We recommend that you add several gallons of water if you can. 
  • Step #4 (optional): If you still can’t add water to your tank, after you have let Tank Cleaner sit in your line for 72 hours, use PEX pipe to poke holes in the top of the pyramid plug. Sometimes you may have an extremely difficult pyramid plug and you won’t be able to add water to your tank even after completing the previous steps. If this happens to you, you can try to knock out the top of the pyramid plug with PEX pipe, a flexible type of pipe that works great for this purpose. To do this, first turn your fresh water off. This will allow you to hold your flush pedal down and keep your toilet line open without filling your toilet bowl with water. Next, send your length of PEX pipe down your toilet line and try to knock out the top of the pyramid plug. As with the other steps, the goal here is to create enough space to add water. If you can create enough space, add 1 bottle of Tank Cleaner and as much water as possible to your tank and let sit for at least 72 hours. 
  • Step #5: After you’ve added water to your tank and let Tank Cleaner work for 72 hours, open your black tank valve and dump your tank. 
  • Step #6: If you have a tank rinser or flusher, run it for 20-30 minutes. You shouldn’t skimp on time with this step! By running your rinser for 20-30 minutes, you make sure to clean all the extra waste out of your tank. When you first start your rinser, the water coming out of your tank might look clear, leading you to believe that your tank is clean, but if you let the rinser run for a while, the residual waste will often break loose and come rushing out of your tank!
  • Step #7: Close your black tank valve and keep it closed unless you’re dumping your tank!

NOTE: Many people wonder if there are any chemicals that will unclog their RV toilet, but the best type of tank openers use bacteria + enzymes to break down the waste that makes up the clog, which is why Unique Tank Cleaner is so effective. It contains no dangerous chemicals and uses only powerful, safe bacteria + enzymes to liquify a pyramid plug.

How to Prevent a Pyramid Plug

As you can see, a pyramid plug is not impossible to remove, but it can be quite the hassle! The absolute best way to avoid these frustrations is to prevent them from ever happening in the first place. 

Like we said above, a pyramid plug forms when the black tank valve is left open. So, to prevent a pyramid plug, simply keep your black tank valve closed unless you’re dumping your tank! This is rule #1 of The Unique Method, our comprehensive guide for treating RV wastewater systems, and it’s extremely important! 

When you keep your black tank valve closed and use plenty of water in your tank (also a rule of The Unique Method), the water in your tank sloshes around and keeps the waste from forming into a pyramid. It also allows a bacteria-based holding tank treatment—like RV Digest-It—to digest the waste inside your tank. On the other hand, when you keep your valve open, all the water flows out of your tank, which means your holding tank treatment will be ineffective and all the solid waste will begin to accumulate into a pyramid of poop! 


We hope that this article has helped you fix your pyramid plug! An RV pyramid plug is definitely frustrating, but it’s ultimately preventable. Even if you’ve already gotten a pyramid plug, however, they can be solved with a little work. 

Like we mentioned in this guide, there are other clogs that can develop in an RV holding tank and toilet, including a blocked line in your RV plumbing and a compacted RV holding tank. To learn more about these clogs, plus how to fix and prevent them, check out our article, Unclogging An RV Toilet!

If you should have any additional issues, or need a question answered that is not covered in this guide, please reach out to us at support@uniquemm.com. We’d love to help you solve your issue!

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