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How to Unclog an RV Toilet Holding Tank?

Writen by Dane Heldt

Fact checked by Robert Clark

How to Unclog an RV Toilet Tank

Not all who go camping want to be one with nature when nature calls, which is why having a clogged black water tank is their worst nightmare. Spare yourself from going number two in the woods. Learn how to unclog an RV toilet holding tank so all of your travels go smoothly.

What Could Have Caused This?

There are several reasons why your toilet is not flushing and some of them are quite simple and easy to fix. The first thing that you should check is the set of valves of the storage tank. Sometimes, the problem is not a clog but an issue with the valves. This means you forgot to open them or they got jarred shut.


Check the valves of your holding tank and make sure that they are all open. If all of the right valves are open and yet your toilet still will not flush then you have a clog. The next most likely culprit of a clogged storage tank is a toilet paper clog.

This type of clog usually happens if you do not use an RV-friendly toilet paper. These dissolve easily in a bit of water, making them easy to flush. This also happens when you forget to fill the toilet tank with water.

The most dreaded black tank clog is referred to as the “poop pyramid”. This happens when you do not close the black water valve after dumping the contents, thus allowing all of the liquid waste to drain out and leave the solid waste to accumulate inside the storage tank.

Even more solid waste matter will accumulate on top of this initial layer of waste. If left unchecked, the poop pyramid will become so massive that it will completely block the entire tank.

How to Unclog an RV Toilet Holding Tank Properly?


Even though having a clogged toilet in your RV is one of the most dreaded situations that an avid camper can face, there are numerous methods that you can try to somehow find a solution to this dreaded problem.

Pouring Hot Water Down the Toilet

If you are dealing with a basic toilet blockage, this very simple yet effective measure is a good place to start. In case you were wondering, no, boiling water will not damage your toilet, plumbing, or black water storage tank.

First, boil a couple of pots of water. Turn off the water main of your RV and then gradually pour the steaming hot water into your toilet. Let the water sit overnight. Hopefully, the clog will be gone come morning. However, if you want to make doubly sure, pour another pot of boiling water and let it sit for half an hour or so before you try to flush your toilet again.

Using Unclogging Chemicals and Other DIY Solutions

If the hot water method did not do anything to help, you can try hot water with a drain unclogger or even just a couple of spritzes of dishwashing detergent. However, since your RV’s plumbing is mostly made of plastics, you should avoid using harsh chemicals like Dran-O and bleach.

One of the most popular DIY solutions is a combination of water softener and dishwashing liquid soap. If you will be using the drain unclogging chemicals designed for RVs, you just need to follow the package directions.

If you will be using the liquid soap and water softener route, you need to pour a cup of liquid detergent into your toilet and then follow it up with the same amount of water softener. Follow by pouring a pot of boiling water and leave the solution to sit overnight.

You can also take your RV out for a drive over a rough patch of road to let the solution slosh around a bit and agitate and loosen up the clog. The following morning, empty the tank and then flush with water.

Using Drain Snakes and Manual Augers

If the clog you are dealing with is particularly stubborn and cannot be dealt with passively then you need to be a bit more hands-on with your approach. For tough clogs, you need to pull out the drain snakes and manual auger.

In some RVs, the toilets flush the waste straight down into the black water tank and if this opening gets plugged up, you just use a plunger to push the blockage through the opening and into the storage tank.

On the other hand, other RVs have an angled pipe to carry the waste from the toilet to the black water tank. This system is more prone to clogging and when it does, it is very hard to clear out. If this is the kind of wastewater system that is in your RV then you need to bust out the plumber’s snake and/or a manual auger if you have one.

Why manual augers? Because it is hard to control electric augers and you might accidentally puncture your plumbing. Here is what you need to do:

  1. Put your plumber’s snake or manual auger into your toilet. Be careful not to scratch the sides.
  2. Feel your way through the plumbing by wriggling the snake/auger.
  3. When you feel as if you have hit the clog, give the handle a clockwise twist until the end of the snake/auger hooks into the offending plug. This might take a couple of tries so do not get discouraged if you do not catch the clog right away.
  4. After you hooked onto the clog, give it a few more twists until it breaks apart and falls through into the black water tank.
  5. Remove the snake/auger and flush the toilet several times to make sure that the clog is gone. Thoroughly rinse the snake using a garden hose and let it dry before putting it back into storage.

Get Help from the Professionals

If you have tried everything that was previously mentioned and your RV toilet still will not flush, give up and just get help from the professionals. If you have tried everything but your toilet still fails to cooperate with you then you just need to throw in the towel and get help from professional RV plumbing services.

These guys do not only have all the necessary tools and equipment to properly get rid of the offending clog. They also have people who know how to use said tools and equipment.

How to Prevent your RV Toilet Tank from Getting Clogged?


You can avoid clogging your RV’s toilet in the first place by practicing proper usage. Here are some of the best practices that you should do:

Use the right TP – You need to use a toilet paper that is specifically made for RV use. These tissues break apart easily in just a bit of water, which is an important feature because the RV toilet does not use nearly as much water as your toilet back home.

Flush often – Even if you are all for conserving water, you should still flush at least twice when you go number 2 in your travel trailer. Many RV users claim that flushing the toilet twice (when you just finished going number 2) will help prevent the formation of clogs soon. For good measure, pour a pot of boiling water into your RV toilet every month or so.

Use more water than paper – Another way to help prevent your toilet from clogging in the future is to use a bidet instead of just tissue paper when cleaning yourself up after going number 2. When you do not use quite as much tissue paper, the chances of a clog forming in the pipes leading to the black water will lessen considerably.

Have some water in the RV toilet holding tank – If you want your RV toilet to work seamlessly, you need to have a bit of water in your black water storage tank. The water will prevent any solid waste from sticking on the sides of the storage tank.

The solid waste sticking against the walls of the storage tank becomes the base from which more solid waste will cling onto. Furthermore, having a bit of water cover the surface of the waste in the tank will prevent smells from seeping out and going out of the opening in the toilet.

Always empty the RV toilet tank regularly – Once you have gone home from your weekend camping trip, you need to empty your RV’s storage tanks. You can either find an RV dumping station that is near you or you can hook the output pipes to your home’s septic tank system or into your community’s sewer line.

Make sure that you empty the black water tank first because the gray water tank contains soapy water that you used to clean your dishes. When you empty the black tank first, the water coming from the gray water tank will help clean the outlet pipe, making cleaning and rinsing a lot faster.


It is a complete nightmare when you wake up in the morning and you find out that your toilet cannot seem to flush properly. Fortunately, there are several things that you do to unclog your RV’s toilet and none of them require the use of simple tools and household chemicals.

When you know how to unclog an RV toilet holding tank, you can rest assured that you will not have any trouble in the future.

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