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Unclogging An RV Toilet

Learn how to unclog an RV Toilet whether you have a pyramid plug, compacted tank, clogged waste line, or misreading sensors

So you think you have a clogged RV toilet. You’re not alone! We get calls from dozens of RVers every single week who are struggling with clogs and backups. As you are probably well aware, nothing can kill the enjoyment of your RV like a disgusting, backed-up toilet!

There are a number of reasons why your toilet might be clogged or appear to be clogged:

  1. you have a pyramid plug, or
  2. you have a blocked line, or
  3. your tank is clogged with compacted waste, or
  4. your sensors are reading full all the time making you think you have a clogged tank

In this guide we’ll give you everything you need to diagnose and get rid of your clog, no matter what the cause. Don't worry. In most cases, this is a very inexpensive and easy fix!

You’re probably reading this article because your holding tanks have started acting abnormally. Here are the most common signs you have a potential clog in your black water holding tank:

  1. You try to add water to your holding tank through your toilet but you can’t add anymore because your toilet bowl is backing up
  2. Your tank shows “full” according to the tank sensors, but nothing comes out when you go to dump your tank. 
  3. You may be able to add more water to your tank, through your toilet, but when you go to empty your tank nothing comes out.

All of these are indicators that you have some issues going on in your tank. Two of them indicate you have some sort of a clog.


Step 1: Diagnose Your Problem

The first phase of unclogging your RV holding tank is to diagnose the problem. There are a number of reasons why your RV toilet might be clogged or appear to be clogged: 

  1. You’ve developed a pyramid plug
  2. You have a blockage in the line between your toilet and holding tank
  3. Compacted waste is clogging your tank or discharge line
  4. You have faulty sensors that are leading you to believe your tank is full when it isn’t

To determine which issue you’re dealing with, follow the steps below to help you get to the root of your problem:


pyramid plug diagram, what a pyramid plug looks like inside your holding tank
DIAGNOSING A PYRAMID PLUG

Open your black tank valve. If nothing comes out you may have a problem. Close your black tank valve. Flush your toilet. Did the water go down the toilet into the tank? If it did, you do not have a pyramid plug. If the water backed up into the toilet bowl instead of flushing down into the tank, either you have a pyramid plug or a blockage in the line between the toilet and the holding tank. We’ll break this down for you...

The tell-tell sign of a pyramid plug (very common) is the fact that water will not empty out of the toilet bowl, into the tank. If you have left your black tank valve open for any period of time, you likely have a pyramid plug. If you never leave your black tank valve open, you likely have a blockage in the line between your toilet and holding tank. Most likely excessive paper has gotten stuck inside the pipe.

Unclogging a pyramid plug is relatively easy. Find the solution to this problem below.



blocked RV toilet line diagram. Unique Camping + Marine
DIAGNOSING A BLOCKAGE IN THE LINE BETWEEN THE TOILET AND THE TANK

IMPORTANT NOTE: Many people think they have a pyramid plug, but in reality, they have a blocked line. The main question you should ask yourself to determine if you’re dealing with a blocked line or a pyramid plug is, did you leave your black tank valve open? If you did, you’re most likely dealing with a pyramid plug. As The Unique Method states, you should always keep your black tank valve closed unless you’re dumping your tank. A pyramid plug can easily develop if you leave your black tank valve open (see below for details). 

If you have kept your black tank valve closed, then you’re probably just dealing with a blocked line, which, thankfully, is pretty simple to fix!

See below to find out what’s causing this issue and for instructions on fixing it!



Completely compacted tank or waste lines  Unique Camping + Marine
DIAGNOSING A CLOGGED HOLDING TANK WITH COMPACTED WASTE

Open your black tank valve. If nothing comes out you may have a problem. Close your black tank valve. Flush your toilet. Did the water go down the toilet into the tank? If it did, you may have a clogged tank. Now, go out and open your black tank valve. Did the water you just flushed come out of the tank? If water came out, you don’t have a clogged tank - you have sensors that are misreading, causing you to believe that there is waste accumulating in your tank when in fact it actually isn’t. If NO water came out, then you have a clogged, compacted tank.

See below to find out what’s causing this issue and for instructions on fixing it!



Diagnosing misreading sensors in your RV holding tanks. Unique Camping + Marine

DIAGNOSING MISREADING SENSORS THAT LEAD YOU TO BELIEVE YOU HAVE A CLOGGED TANK

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).



What’s Causing My Tank To Get Clogged?


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 grossness that has now reached your toilet and is clogging it up. When dealing with a clogged RV toilet, many people incorrectly assume that their holding tank is totally full. For a very few people, this may indeed be the case, but for most people, the culprit is not a completely clogged tank but, in fact, a pyramid of solid waste that has built up from the bottom of the tank and is now touching the base of your toilet.

To understand why you get a pyramid plug, you first have to understand that your holding tank is essentially flat on the bottom. Why is this important? Well, most people who get pyramid plugs do not follow Rule #1 of The Unique Method: KEEP YOUR BLACK TANK VALVE CLOSED. This is an important point, because if you follow The Unique Method, most of these issues would have been prevented in the first place (see below)!

Here’s how a pyramid plug develops:

When your black tank valve is kept in the closed position during normal operation, the solid and liquid waste accumulate in your tank and slosh around. When you dump, all of that sloshing waste should flow out smoothly.

However, if you keep your black tank valve in the open position during normal operation (which you shouldn’t!), every time you use the toilet, the liquid waste flows freely out of the tank and into the sewer, but because your tank is flat on the bottom, the solid waste accumulates. Over time, if you keep adding more and more of that solid waste, you will begin to build a pyramid plug.


Blockage In The Line

When you’re dealing with a blockage, waste (most likely toilet paper) has built up in the line between your toilet and your holding tank and is causing water to back-up into your toilet bowl. A blockage in your line normally occurs in RVs where the toilet is located farther away from the holding tank. While most RVs have toilet lines that drop directly downwards into the black tank, others have long lines with elbows. It’s at these elbows that toilet paper normally builds up and causes blockages.

Many people think they have a blocked line when in fact they have a pyramid plug. The reason these often get confused is because these issues share the same symptom: you can’t flush your toilet, because water won’t go down the line. 


Compacted Tanks

A compacted tank is less common than pyramid plugs or blocked lines but no less frustrating! There are a few ways that a compacted tank could develop:

1) You have solid waste that has accumulated in your holding tank and is inhibiting the tank from dumping properly. This typically happens because you aren’t using an effective waste digesting treatment and/or because you aren’t following the right treatment process, like The Unique Method.

This can also happen because you didn’t dump your tank before storing your RV and the waste has dried up and turned into a solid brick of waste. This, by far, is the worst way to develop a compacted tank. When 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 become extremely solid. But, lucky for you, our products will still remove it (see recommendations below)!

2) You have solid waste or toilet paper stuck in your discharge line (the line where your waste water comes out of the RV when you dump your tank) because you haven’t been using a good waste-digesting toilet treatment and/or are using the wrong treatment process.


Misreading Sensors

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

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

Misreading tank sensors in your black tank are caused by poop and toilet paper that coat the surface of your sensor probes. These sensors typically work by completing an electrical circuit once the water inside the tank reaches the level of the sensors. But when poop and toilet paper cake onto the surface of your sensors, they complete the electrical circuit, which causes your sensors to read “full” when your tank is actually empty or only partially filled.


Step 2 - Unclogging Your RV Holding Tank


Pyramid Plug

As we said above, a pyramid plug can often be mistaken for a blockage in your line between your toilet and your holding tank. But, like we mentioned above, one easy way to determine if you have a blockage or a pyramid plug is to ask yourself, do you keep your black tank valve open? If you do, you probably have a 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. Some product will likely seep through the top of the pyramid plug and open a channel into your tank. If you can get this to happen, 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!) 

Sometimes, however, the recommendations given above won’t cut it. You still won’t be able to get water into your tank. In this case, we recommend that you go down to the hardware store and purchase 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. 

The idea is to use a flexible PEX pipe to break up the top of the pyramid plug, creating enough space to get water into the tank. Here’s how to do it: first, turn off your fresh water. 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 flush valve open (not to be confused with your black tank valve, which should remain closed), 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 or at least create enough space to get some water and Tank Cleaner into the tank. 

If you can create enough space to add water, pour 1 entire bottle of Tank Cleaner into your tank through your toilet and add as much water as possible. Let the product work for as long as you can (typically we recommend at least 72 hours for the most effective cleaning). There is no amount of 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. 

After you have allowed Tank Cleaner to work for a significant amount of time, 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 a long time to ensure the contents that were broken up by Tank Cleaner rinse completely out of your black water tank. Often, when you first start your rinser, you'll see clear water coming out, but don’t assume that your tank is completely clean. Normally you’ll find that if you let the rinser run longer, at some point the waste will break loose, and you'll see a tidal wave of brown water come pouring out of your tank. This can often last for several minutes!

Close your black tank valve and keep it closed so you don’t get another pyramid plug! Also, you may need to repeat the process given above a few times to make sure the tank is completely clean. 

Here’s a quick summary of the steps given above:

  1. CLOSE YOUR BLACK TANK VALVE. (Always keep it closed unless you’re dumping your tank.)
  2. Pour 1 entire bottle of Tank Cleaner into your toilet and add several gallons of water by flushing the toilet. If you can’t add any more water because water is backing up into the toilet bowl, turn off your fresh water supply and use PEX pipe to gently poke holes into the waste clog so you can get more water into the tank. The more water you can add to the tank, the better, so fill up your holding tank as much as possible (without making a mess!).
  3. Let sit for as long as possible (we recommend a minimum of 72 hours for best results). After the treatment period, the solids in your holding tank should be broken up and liquefied.
  4. Open your black tank valve and dump the tank.
  5. Rinse your tank for 20-30 minutes with your built-in tank flusher or wand so that the tank is thoroughly rinsed out.
  6. CLOSE YOUR BLACK TANK VALVE, and only open it when you're dumping so you never have to deal with this problem again!

If you’ve tried all the recommendations given above, and you still aren’t seeing results, please reach out to us at support@uniquemm.com. We are happy to help you get your tanks back on track!


Blockage in the Line

As mentioned earlier, a blockage in your line between your toilet and your holding tank is often confused with a pyramid plug, but normally, it’s much easier to fix! 

The steps for removing a blockage will be very similar to removing a pyramid plug. With that being said, try using a toilet plunger to force the blockage out first. There is no reason why a plunger wouldn’t work in this situation. All you are trying to do is push the blockage out of your line and into your holding tank, so applying that pressure with a plunger can often do the trick. All the same, you may need a little extra help. This is where Unique Tank Cleaner comes into the picture. Pour 1 bottle of Tank Cleaner down your toilet and let it sit overnight. Plunge it again in the morning. 

If these solutions don’t work, try using a snake or PEX pipe. A snake or PEX pipe will allow you to easily get through all those twists and turns in your line. As we’ve established already, poking out a clog or blockage with a snake or PEX pipe can be very effective!

Here’s a summary of the points we just covered: 

  1. If you think you have a blockage in your line, try to plunge it out first. 
  2. If a plunger doesn’t work, try pouring 1 bottle of Tank Cleaner into your toilet bowl and let it sit overnight. Try to plunge your toilet again in the morning. Tank Cleaner will start to break up the blockage or, if you actually have a pyramid plug, will start to eat away the top of the plug and allow you to add water to your tank.
  3. If nothing else works, try a snake or PEX pipe.

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! With that said, sometimes the compacted waste on the bottom of the tank can be extremely solid (especially if it has been allowed to dry while the RV was in storage), so though it may be easier to fix, it can sometimes take significantly longer for Tank Cleaner to break up this hardened waste.

As you might have guessed, 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 sit for as long as possible. If you’re dealing with a compacted tank, we recommend allowing Tank Cleaner a minimum of 72 hours to work. Open your black tank and allow the tank to empty out. Flush your tank with your built-in tank rinser or wand for 20-30 minutes.

If all has gone well, 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 a shoe or other device, like a rubber mallet. This can help to dislodge any chunks of waste stuck in the pipe or discharge port. Again, just as a caution, 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. 

Here’s a summary of the points given above:

  1. CLOSE YOUR BLACK TANK VALVE. (Always keep it closed unless you’re dumping your tank).
  2. Fill the tank with water.
  3. Pour 1 entire bottle of Unique Holding Tank Cleaner into the tank through your RV toilet. 
  4. Let sit for as long as possible (we recommend a minimum of 72 hours). After the treatment period, the waste inside your black tank should be liquified.
  5. Open your black tank valve and dump your tank.
  6. Run your tank rinser or flusher for 20-30 minutes.
  7. If the tank won’t empty, let Tank Cleaner work for a little longer. Gently tap the discharge pipe, which may help to dislodge some chunks of waste.
  8. CLOSE YOUR BLACK TANK VALVE.

If you’re still having issues after following all the steps above, please contact us at support@uniquemm.com!


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. 


Step 3: How To Prevent Clogs In Your RV


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 the waste to remain in a liquid solution inside your tank, so the solid waste can break down and dump effectively). 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. This treatment process will prevent virtually all odor, clog, or sensor problems.

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.


Blockage in the Line

To prevent a blocked line, make sure to use plenty of water. First, always fill your toilet bowl with water before using the toilet. Second, hold your flush peddle down for 10 full seconds each time you flush the toilet. This will help to flush the solid waste down the line effectively, decreasing the chances that toilet paper will build up in the line and cause a blockage. These points are covered in detail in The Unique Method, which we recommend that you follow to help prevent blocked lines!


Compacted Tanks

To prevent a compacted tank, first make sure that you keep your black tank valve 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 (and 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 of 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-consuming 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 prevented by using a high quality waste digester, like RV Digest-It and by following The Unique Method. It’s also a good idea to perform a regular deep clean of your tank using Unique Tank Cleaner. Like most of these recommendations, this process is part of The Unique Method. You can learn how to perform a deep clean on your holding tanks with this guide.


Conclusion

We hope that this article answers all of your questions about your clogged RV toilet! If after following all the guidelines above, you should still find yourself in this putridly poopy predicament and need further assistance, please don't hesitate to reach out to us at support@uniquemm.com. We're more than happy to help you get your toilet issues back on track!

Happy Camping!