There are so many fun things about RVing, but toilet clogs aren’t one of them. Before you can fix an RV toilet clog, you need to determine which type of clog you have. Each type of camper clog requires different methods to fix, so we’re here to explain the types of RV clogs there are and how to accurately diagnose your problem so you can fix it properly.

Key Points About RV Toilet Clogs

• There are three main types of RV toilet clogs: pyramid plugs, compacted holding tanks, and blocked toilet lines.
• Accurately diagnosing the clog you have is important so that you can take the appropriate steps to fix the problem.
• Each type of RV toilet clog needs to be approached differently.
• Misreading sensors may falsely indicate you have a clog, when you actually don’t.

Types of RV Toilet Clogs

There are three main types of RV toilet clogs that you could be facing: pyramid plugs, compacted holding tanks, and blocked black water plumbing. We’ll provide details about each of them so that you can become more familiar with what may be happening in your RV.

1. RV Toilet Clog Type: Pyramid Plug

What is an RV Pyramid Plug?

Pyramid plugs, also sometimes known as poop pyramids, develop slowly over time as waste and toilet paper accumulate into a pyramid shape right below the RV toilet line. When this happens, the pyramid can become so large that it blocks off the pipe and prevents you from adding anything else into the tank.

How Do RV Pyramid Plugs Happen?

The most common cause of RV pyramid plugs is when RVers leave their black tank valve open when full-hookup camping.

While it may seem logical to leave the black tank valve open to allow everything to naturally flush out, unfortunately, when you do this, all of the liquid will flow out as expected, but all of the physical waste and toilet paper tends to remain.

As the toilet continues to be used, the waste and toilet paper can stack on top of itself until the pyramid grows so large that it creates a clog by blocking off the pipe.

For full details about pyramid plugs, we recommend reading our guides:

• What is an RV Pyramid Plug?
• How to Remove an RV Pyramid Plug?

2. RV Toilet Clog Type: Compacted Black Water Tank

What is an RV Compacted Black Water Tank?

Compacted tank clogs occur when an RV black tank has a large amount of waste that has hardened inside the tank. When this happens, solid waste blocks the exit and nothing can flush out of the tank when the black tank valve is opened.

How Do RV Compacted Black Water Tank Clogs Happen?

The most common cause of RV compacted tank clogs is when the RV has been in long term storage with a full, or partially full, black water holding tank.

As the RV sits in storage, the liquid evaporates from the black water holding tank, leaving behind a brick of waste and toilet paper that creates the clog.

Additionally, not using a high-quality, waste-digesting treatment or a leaky discharge valve can be other causes of compacted black water tank clogs.

For full details about compacted tank clogs, we recommend visiting our guide: How to Unclog a Compacted RV Black Tank

3. RV Toilet Clog Type: Blocked Toilet Line

What is an RV Blocked Toilet Line?

Blocked RV toilet lines, or clogs in black water plumbing in general, occur more quickly than other types of clogs. These clogs happen as waste and toilet paper move through the relatively narrow plumbing pipes and create a blockage.

How Do RV Blocked Toilet Lines Happen?

The most common cause of blocked toilet lines in RVs is flushing too much toilet paper, and not enough water down the toilet.

Blocked plumbing lines are more likely to occur when the black water tank isn’t situated directly below the toilet and the paper and poop has to travel through long lengths of pipe that may include turns and elbows in the plumbing, or because waste must travel between two black water tanks.

For full details about how to deal with RV blocked toilet lines, review our guide: How to Unclog a Blocked RV Toilet Line

Misreading Sensors & RV Toilet Clogs

Sometimes, holding tank sensors that are caked with waste, toilet paper, and debris (black water tanks), or grease and oils (gray water tanks), can misread and falsely lead you to believe you have a clog.

Misreading sensors may tell you that the black water tank is full, but then nothing comes out when you open the black water tank valve. This could signal that you have a compacted tank, but it could also mean that you simply have an empty tank with sensors falsely reading that the tank is full. In some situations, it is even possible that you’re dealing with a clog and misreading sensors at the same time.

Fortunately, resolving these issues is relatively easy. For help with misreading sensors, refer to our guide: How to Clean and Restore RV Holding Tank Sensors

Determine What Type of RV Toilet Clog You Have

Now that you know the three types of camper toilet clogs you may be dealing with, we are going to help you determine which type of clog you actually have. It’s very important to know what type of clog there is, because you need to use a different method to fix each type.

How to Diagnose Your RV Toilet Clog

Before trying to diagnose your RV toilet clog, we highly recommend being in a location with access to a sewer port, such as a full-hookup campground or dump station. This will give you the opportunity to do a more thorough diagnosis.

Now let’s dive in and figure out what type of RV toilet clog you have:

1. Add water to your black tank through your RV toilet bowl.
   • Does the water collect in the toilet bowl when you push down the flush pedal?
     • If the answer is yes, you may have a pyramid plug or blocked toilet line.
     • If you’ve left your black tank valve open for any period of time, you may have a pyramid plug.
     • If you never leave your black tank valve open, you may have a blocked toilet line.
   • Does the water easily flow into the black water tank? If the answer is yes, you may have a compacted tank or misreading sensors.
2. Turn off all water sources to the RV.
3. Connect the sewer hose to the discharge port of your RV.
4. Open your black tank valve.
   • If water flows out of the tank when you open your black water tank valve, then you may simply have misreading sensors.
   • If nothing flows out of the tank when you open the black water tank valve, you may have a compacted tank.
5. Shine your flashlight down the toilet for additional information.
   • Do you see the peak of a pyramid plug near the bottom of the pipe that connects the toilet to the black tank? If the answer is yes, you likely have a pyramid plug.
   • Do you see that the pipe is completely blocked off with paper debris? If the answer is yes, you probably have a blocked toilet line.
6. Turn the water sources to the RV back on.

Reviewing RV Toilet Clogs

Dealing with a clogged RV toilet can be a huge pain, but we hope this guide helps you understand the three main types of RV toilet clogs – pyramid plugs, compacted tanks, and blocked toilet lines – and how to determine what type of clog you’re dealing with. Accurately diagnosing your clog will help you use the correct method to resolve the problem, and get you back to enjoying life on the road.

For more information about how to prevent RV toilet clogs in the future, we recommend reading our guide about Preventing Clogs in Your RV Black Water Holding Tanks.