How to Unclog an RV Toilet or Black Tank and Prevent Future Clogs

RV toilet
If you've owned an RV for any amount of time you may have experienced a clog in your toilet or black tank. If so, you know how much of a hassle it is to deal with. Join us as we discuss some easy ways to clear that clog and some of things you can do to prevent it from ever occurring.

Unclogging your RV toilet comes down to breaking up the solid waste that has been building up in your black tank and flushing it out. Once the cause of the issue has been addressed, it is time to implement some basic maintenance to prevent future issues.

Why is my RV toilet backing up?

The most common reason for this problem is the infamous “poop pyramid”. If you’ve ever seen the poop emoji on a cell phone, you know what I’m talking about.

What is a poop pyramid?

If you’re not familiar, I will reluctantly elaborate. A poop pyramid is the result of a continuous buildup of solid waste in your black tank. This waste starts stacking in a vertical pile and will make its way upward, towards the toilet.

Why does a poop pyramid occur?

Keep in mind, most RVs have a direct connection from the toilet to the black tank. This means that anything in the toilet drops directly into the black tank when the toilet is flushed. This creates an environment where the poop pyramid can easily form and harden over time.

Outside of waste directly dropping into your black tank, a lack of liquid in the tank may be the biggest contributing factor. You need to have some liquid in your black tank for it to function properly. We will discuss this more down below.

Another cause, which occurs less frequently, is when your black tank has a leak. This will cause any liquid to drain and it creates a ripe environment for waste to build up.

What are the symptoms of a poop pyramid?

There are typically two different things you can look for when discovering this issue. First, you may visually see the pyramid forming when you look through the bottom of your open toilet. If this is the case, you may have discovered it before any major issues.

Secondly, you may find out late in the game when your toilet starts to clog and won’t drain. This occurs when the pyramid has grown to a height where it blocks the toilet from draining properly.

What do you do when your RV toilet is clogged?

The first thing you can try is a very effective method and is completely free. Here’s what you do to give it a shot:

  1. Fill our sewer hose with gray water keeping the exit end elevated
  2. Close gray water and make sure the black water valve is open.
  3. Lift the sewer hose from the exit end force graywater into the black water tank.
  4. Once the graywater runs into the black water tank, drop the hose to create a vacuum and let is suck everything back out to unclog.

If that is as clear as mud, take a look at this video for a visual explanation.

Other Methods to Clear a Clog

Flush King

The Flush King is basically a reverse flush valve attachment that hooks directly to your sewer connection. It has built-in safety features to prevent contamination of any freshwater and is made from a clear material, allowing you to see when the water starts running clear.

Swivel Stick

The Swivel Stick is another option worth looking at. It’s basically an extension you hook water to and it dispenses the pressurized water in a rotary type method. The stick can also be used to break up any solids on the way down if need be.

You can control the pressure, which can be important when using this tool. Be prepared, you may catch some residual spray coming back out of your tank and through the toilet. Proceed with caution…haha.

Fill and Soak

If you are patient and have the time, you can always try the fill and soak method. This technique is pretty much just like it sounds. Simply fill your black tank with water and let it soak. This may take quite some time and multiple tries.

You basically fill the tank with freshwater and let it sit. The idea is to let the water slowly rehydrate and soften the solid waste. After a few days, you damp your tank and see what comes out. Remember, you may have to do this several times and it can test your patience.

Water and Ice

If you are in a bit more of a rush and you don’t mind taking your rig on a quick drive, the water and ice method may be for you.

For this technique, you are going to get your hands on a decent amount of ice. I usually try about 4-5 bags if possible. Once you get your ice, dump them into the toilet and directly into the tank, if possible, and go for a drive.

The idea is to let the agitation of the ice work to break up the solids. As it melts, it will provide the liquid to aid in flushing. I recommend filling the tank the rest of the way up prior to dumping as well. The larger volume of water will help to clear out the solids.

Chemical Treatment

Another option is to go the chemical route. I recommend using RID-X as one of many options. This takes time as well and is more of a set it and forget it method. Simply drop it in your toilet, flush, and let it go to work. The bacteria and enzymes will work to break down all the nastiness in your tank.

Organic Treatment

For an organic option for those with time on their side, I love Happy Campers. It’s odor-free and 100% tank friendly. It’s always worked well for us and gives us that extra peace of mind. As a bonus, it works with all toilet paper types.

A Stick and a Prayer

If all else fails, and you don’t have anything available to use, go find a stick. Yep, a stick. Use it to break up the clog so things can start moving and shaking again. Be sure to fill up your tank prior to dumping.

Can I use Drano in my RV toilet?

Drano is not recommended. It is best to stay away from harsh caustic chemicals as a precaution. Some of these chemicals can have negative affects on the black tank construction. You want to avoid anything that will degrade or compromise this system.

Can I Snake an RV toilet?

Yes, you can snake an RV toilet and sometimes it may be necessary if you have a toilet that does not dump directly into your black tank. This also works well for toilets with smaller openings. Sometimes this action is needed to break up stubborn clogs.

How to Prevent my RV Toilet From Clogging

As with most things, prevention is key. It’s much easier to prevent these issues than having to deal with them after the fact. Let’s look at a few things you can do to avoid these messes altogether.

  • Make sure you’re not leaving the black tank valve open even at a full hookup.
  • Make sure there is enough gray water to flush after emptying black tank…as in, leave both valves closed until dump time.
  • Use the Flush King to backflush and keep your tank free of buildup.
  • Use more water than you think when you flush. Think of how much water a regular toilet uses to flush.
  • Use internal tank flush every couple of weeks if your rig has one.
  • Use a Swivel Stick on a regular basis to clean the walls of your black tank.
  • After you dump, add 5 gallons of water and your chemical (Happy Camper) or a cup of Calgon and a cup of Dawn (Geo Method).

You don’t have to do all of these, so just find what works for you.


Prevention is key, but if you haven’t had the best maintenance practices, don’t sweat it. If you get a clog, it typically just takes a little elbow grease and a strong nose.

If you have any tips that work for you, please feel free to share.

Happy Camping!



Leave a Reply

Your email address will not be published. Required fields are marked *

Table of Contents

You might also like

Related posts