Clearing RV Toilet Clogs

October 11, 2019

How to unclog a plugged camper toilet RV motorhome holding tank step by step

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Key Points:

  • RV toilet clogs are caused by three main issues: pyramid plugs, compacted holding tanks, or a blocked toilet line (misreading sensors can also cause you to believe you have a clog).
  • Diagnosing which type of toilet clog you are dealing with is crucial to solving your problem.
  • There are easy fixes for all three types of RV clogs.
  • Preventing clogs is as easy as following The Unique Method on a regular basis.

Using an actual toilet while camping is probably a big reason why you bought an RV in the first place, so dealing with a clog is never a fun experience. You’ll be happy to know that we get calls from dozens of RVers (even seasoned pros) every single week who are struggling with how to unclog an RV toilet and prevent backups, so you’re not alone. In this guide we’ll give you everything you need to diagnose, fix, and prevent your camper clog, no matter what the cause.


What Type of RV Toilet Clog Could I Have?

There are three types of toilet clogs that you could be dealing with:

RV Pyramid Plug Diagram. How to unclog a pyramid plug. Unique Camping + Marine
Pyramid Plug

This is poop and toilet paper that accumulates into a pyramid shape right under your RV toilet line and has finally reached the top where it is now preventing anything from being added to the tank. A pyramid plug usually occurs when you have left your black tank valve open while on hook-ups because any liquid added to the tank immediately drains out of the open valve allowing accumulated waste to dry and build up. Always leave your black valve closed unless actively dumping a full tank. For more details on pyramid plugs, refer to our What is a Pyramid Plug guide.

Compacted RV holding tank diagram. What is a compacted clog? Unique Camping + Marine
Compacted Tank

A compacted tank just means that solid waste has accumulated in the bottom of your black tank, preventing waste from exiting the tank when the valve is opened. This can occur if you are not using enough water in your tank, not using a high-quality, waste-digesting treatment, have a leaky discharge valve, or waste was left sitting in your tanks while in storage, which means the liquids eventually evaporate and the poop dries out, making it much harder to clean when you’re ready to use it again.

Blocked RV Toilet Line Diagram. Unique Camping + Marine
Blocked Toilet Line

A blockage of toilet paper and solid waste can become trapped in the actual pipe that leads from the toilet bowl to the black tank. This problem mostly occurs in RVs where the toilet is not situated directly over the black water tank and the plumbing system therefore has turns and elbows where waste and TP can easily become congested. With systems like these where the toilet pipe does not empty vertically into the tank, it's best to use more water than you may think necessary when flushing. This type of clog shares the same symptom as a pyramid plug but has a slightly different fix, so be sure you know exactly which type of issue you are dealing with.

Misreading Sensor Probes Diagram. Unique Camping + Marine
Misreading sensors

Are often caked with waste and toilet paper debris (black tanks) or grease and oils (gray tanks). They can sometimes falsely indicate you have a clog, telling you the tank is full but nothing comes out when you open the black valve. It could be a compacted tank or it could just be an empty tank that has sensors falsely reading full. If all you have is misreading sensors, it is an easy fix. Refer to our How to Clean and Restore RV Holding Tank Sensors guide.

In the next section, we will help you narrow down exactly what kind of clog you are dealing with so you can quickly take care of the issue.


Determine the Type of RV Toilet Clog

Knowing the type of clog you are dealing with is very important because there are different techniques you may need to use to free one clog as opposed to another type. We have provided a very easy litmus test below to help you determine what kind of issue you are experiencing, and then we’ll show you how to fix it!

Add water to your black tank through your RV toilet bowl.

  1. If the water quickly collects in the toilet bowl, you have a blocked toilet line or a pyramid plug.

    • If you have left your black tank valve open for any period of time, then 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.

  2. If the added water easily flows into the black water tank, you have a compacted tank or misreading sensors.

    • If the water flows out of the tank when you open the black valve, you probably just have misreading sensors. Refer to the How to Clean and Restore RV Holding Tank Sensors guide.

    • If nothing comes out of the tank when you open the black valve, you have a compacted tank.


How to Clear All Three Types of Clogs


Clearing a Pyramid Plug

A pyramid plug can sometimes be confused with a blockage in the line because they both share the same symptom: water pools in the toilet bowl because the blockage prevents water from reaching the tank, so be sure to use the diagnosis tool above to determine which type of clog you have. Even though a pyramid plug will stop waste and the majority of liquid from going into the tank, sometimes a little bit of water can still get through; if it’s clear there is no channel for liquid to pass into the tank, you’ll need to make one, even if it's small and the water passing through is slow. Before you start, make sure your black tank valve is closed.

  1. Turn off your fresh water.

  2. Pour one entire bottle of Unique Tank Cleaner into the toilet bowl, and hold down the flush pedal so the product gets to the clog.

  3. Let the product sit in the toilet for a few hours.

    • If the liquid solution in the toilet has fully or partially emptied into the tank, then you have a channel. Fill your tank with as much water as possible and let sit for a minimum of 72 hours.

    • If the liquid solution in the toilet has NOT appeared to drain much at all, hold down the flush pedal, and use a PEX pipe or toilet snake to poke a hole in the top of the pyramid plug. Once you've created a big enough channel, fill your tank with as much water as possible and let sit for a minimum of 72 hours.

      Note: No amount of time is too long for Unique Tank Cleaner to work, but we typically recommend at least 72 hours.

  4. After 72 hours, dump the tank.

  5. Perform a black tank flush for 20-30 minutes with a rinser wand or back flusher.

    Note: You may see clear liquid coming out of the black tank discharge port when you first begin rinsing, but this doesn't mean you've cleared the tank of all the waste making up the pyramid plug. After more time rinsing, you'll probably break apart any remaining stubborn waste and you should start seeing more of the nasty water you were expecting. This tidal wave of poop water could last for several minutes, so keep flushing until the water is mostly clear.

  6. Repeat this process again if you suspect there may still be a stubborn build up of waste that was not knocked out the first time.

  7. Don’t forget to turn your fresh water valve back on once you’ve cleared the clog.

    Important: When you are finished, be sure to close your black tank valve and keep it closed unless you are actively dumping a full tank.

If you’ve followed the entire process above and still aren’t seeing results, please reach out to our customer support team. We are happy to help you get your tanks back on track!


Clearing a Compacted Tank

A compacted tank can be less of a headache to fix initially because the toilet pipe isn’t blocked by anything, so it’s easy to add water and product to your black tank. However, 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 add water and cleaners to the tank, it can sometimes take significantly longer to break up the hardened waste.

  1. Close your black valve and fill the tank with as much water as possible.

  2. Pour one entire bottle of Unique Tank Cleaner into your tank through the toilet.

  3. Let the water and tank cleaner solution sit in the tank(s) for at least 72 hours.

    Note: We always recommend at least 72 hours for tank cleaner to work, but with compacted tanks, you may need to let it sit for longer than that because the waste is sometimes so solid that the solution needs more time to break it up.

  4. Open the black valve and dump the tank(s).

    • If nothing comes out, close the valve again and let Unique Tank Cleaner work for longer, possibly another 72 hours if you are able. If the blockage in the discharge line is very stubborn, you may need to use a PEX pipe to break up the waste so the rest can flow out.

    • If water starts coming out, dump the tank as normal.

  5. Perform a black tank flush for 20-30 minutes with a rinser wand or back flusher.

  6. Close your black valve.

  7. Repeat this process again if you think there may still be some stubborn waste on the floor of the tank; as we said, you may need to let Unique Tank Cleaner work for longer than 72 hours to get every piece of waste to loosen.

If you’ve followed the entire process above and still aren’t seeing results, please reach out to our customer support team. We are happy to help you get your clogged RV holding tanks back on track!


Clearing a Blockage in the Line

A blockage in the toilet line can sometimes be confused with a pyramid plug because they both share the same symptom: water pools in the toilet bowl because the blockage prevents water from reaching the black water tank, so be sure to use the Determine the Type of RV Toilet Clog section above to confirm which type of clog you have. A blockage in the toilet line usually occurs in RVs that have bends in the plumbing pipes where too much toilet paper and solid waste can easily get snagged; not sending enough water along with the TP and waste can also cause a problem in RVs with bends in the sewage pipes. Thankfully, fixing this blockage can be as easy as how you fix toilet clog in a home toilet with a plunger. If a simple plunge doesn’t work, the process is similar to fixing a pyramid plug.

  1. Turn your fresh water off and hold down the flush pedal.

  2. Use a toilet plunger to try and force the blockage out of the line, just like you would in a home toilet.

    • If the plunger clears the blockage, turn the fresh water back on and hold down the flush pedal for a while to cleanse the pipe of any residual debris still hanging on; dump and flush the black water tank if necessary. You’re done!

    • If the plunger doesn’t clear the blockage, hold down the flush pedal and pour in one entire bottle of Unique Tank Cleaner.

  3. Let it sit in the toilet overnight.

  4. Try to plunge the toilet again the next morning.

    • If the blockage is cleared, turn the fresh water back on and hold down the flush pedal for a while to cleanse the pipe of any residual debris still hanging on; dump and flush the black water tank if necessary. You’re done!

    • If it does not clear, try using a PEX pipe or toilet snake to push the blockage down the line and into the tank. Once it clears, turn the fresh water back on and hold down the flush pedal for a while to cleanse the pipe of any residual debris still hanging on; dump and flush the black water tank if necessary. You’re done!


Misreading Sensors Falsely Indicating a Clog

Some people mistake misreading sensors for a clogged black water tank. Your sensors may tell you that the tank is full, but when you open the black valve to dump, nothing comes out of the tank. If you’re sure the tank is empty, then you probably just have debris caked on the sensors. The best way to confirm that the problem is just misreading sensors is to add water to the tank through your toilet:

  • If nothing comes out of the tank when you open the black valve, then you have a compacted tank.

  • If you can dump it out of your discharge port but the sensor still shows full, then you’re probably just dealing with misreading sensors.

Refer to the How to Clean and Restore RV Holding Tank Sensors guide to return your sensors to proper working order.

If you follow the process for cleaning sensors and they are still misreading, they may simply be broken and need to be replaced.


Preventing RV Toilet Clogs

Prevention is always the key when it comes to RV toilet clogs. The best way to prevent any type of clog is to follow The Unique Method, which is our proven process for treating RV black water tanks. The Unique Method is a 50/50 approach that requires 50 percent the right care habits and 50 percent the right products. We always recommend our products when using The Unique Method because they were formulated with The Unique Method in mind, which means you get the best possible results.

Refer to the Preventing Clogs in Your RV Holding Tank guide for more information on the best ways to prevent toilet clogs.


Review

Unclogging an RV black tank is never fun, but now you have the resources you need to stop RV toilet clogs from ever forming in the first place and to fix them if they do emerge. Here’s a brief review of what we covered in this guide:

  • There are three different types of RV toilet clogs: pyramid plug, compacted tank, blockage in toilet line.

  • Misreading sensors can cause you to assume you have a toilet clog.

  • Fixing a pyramid plug will require one bottle of Unique Tank Cleaner, lots of water, and possibly a PEX pipe or RV toilet snake.

  • Fixing a compacted tank will require at least one bottle of Unique Tank Cleaner and possibly much longer than 72 hours for it to work.

  • Fixing a blockage in the line could be as easy as using a plunger; more serious blockages could require the use of Unique Tank Cleaner and/or a PEX pipe or RV toilet snake to push it through to the holding tank.

Preventing RV toilet clogs is as easy as following the guidelines in The Unique Method.




Adopt The Unique Method

You bought your RV so you could enjoy life and spend time with family and friends. The last thing you want to do is waste precious time and money on fixing wastewater holding tank problems. Keeping your tanks in peak operating condition doesn’t have to be hard, confusing, or expensive if you follow our proven process: The Unique Method.

The Unique Method is a comprehensive tank care plan that we developed after years of conversations with real customers facing real problems. The Unique Method provides you with simple, preventative steps to stop odors, clogs, and sensor problems before they start so you can spend less time worrying about your holding tanks and more time enjoying the freedom and adventure of RVing. Try it yourself and see why thousands of campers trust their RVs with The Unique Method every day.

If you need more help with anything covered in this guide or simply have a comment, we’re here to help you anytime!

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