Written by 9:28 pm Common Questions

How To Unclog An RV Toilet (Step-by-Step)

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Is Your RV’s Black Water Tank Plugged? If Your Toilet Is No Longer Flushing, It Just Might Be!

Below, I will show you how to unclog your black tank, and how to prevent it from giving you any trouble in the future.


The RV life is not always the most glamorous life. Sometimes it requires a little down and dirty work. That is never more evident than sewer maintenance. Coming face-to-face with your body’s waste is honestly a little bit disturbing. It’s even worse when your sewage system gets all plugged up. Still, it is part of the life that we have all chosen, so there is no point complaining about it. If you are here, then you are probably about to participate in this filthy tradition. If so, then dress up in your worst clothes, pull up your sleeves, and put some gloves on; it’s time to work.


The Pyramid Plug

The Aztecs and the Egyptians certainly don’t have a patent on pyramid building. In an affront to their careful craftsmanship, it is probable that you have unknowingly built one of your own. In the industry, the most common form of plug is known as the Pyramid Plug. Most of the time, these pyramids are the cause of the black water tank blockages. Yes, like a carefully arranged Jenga set, you stacked your pillars into a classic configuration and plugged the toilets pipeline. Sadly, your work of art must go, and I’m going to tell you how to topple that tower.


Close the Valve During Operating Business Hours
Remember to close your black water valve unless you are actively emptying your tank. When you flush, everything from the toilet gets emptied into the black water tank. That tank is designed to hold the poop, the paper, and the water. It is supposed to create a hidden water-world inside the black tank. However, when the valve is in the open position, it allows the water to flow out of the tank. When the water is allowed to continually flow out of the main area of the tank, the poop will begin to stack on the mostly dry surface(instead of free-floating in the water). As it stacks, the water has an increasingly difficult time of moving the growing pile. Eventually, the stack will reach the pipes, and you have successfully created a clog.


Method Number One: The Simple Method

What Do I Need?

  • Unique Tank Cleaner or a Comparable Product
  • Buckets, Jugs, or a Hose to add Water
    (Whatever you use, be careful of nasty splashbacks)


As a bit of a germaphobe, I must say that I hope this one works for you. The other method isn’t bad, but the less hands-on work the better. This method will require a bit of time (12 hours), so skip over to the second method if the fix needs to happen sooner rather than later.


Step 1: Check the Valve Position

Most likely, the valve has been left open, so the black tank is probably a bit dry. We need to turn that desert into a lake, so the first thing to do is to go make sure that the valve is closed.

Step 2: Fill the black tank with water

When confirmed or the position is fixed, you will want to fill that tank with water. You will do this by adding water to the toilet or adding the water directly into the toilet’s flush pedal. More water is considered better by the experts, but some say that a few gallons should work. Remember, you are likely trying to destabilize a sizable structure, so picture what is happening. Do you feel less stable in a foot of water or a few feet of water? More water also means that the cleaner will have more contact with the blockages and more water to wash them away.


Step 3: Add the Unique Tank Cleaner or a Comparable Product
After the tank is filled with water, add the water tank cleaner. You probably shouldn’t need to worry about the product diluting; it should be strong enough to handle the job…Still, I would check to see that it was designed to handle a tank your size so that you don’t need to make a second trip.


Step 4: Wait for at least 12 Hours
The microbes in the product need a little time to erode away at the pile of waste, so leave it there for at least 12 hours. According to the Unique Cleaner website, the waste will be “liquefied” and ready for removal.


Step 5: Hook up to the Dump Station and Release
At this point, your tank should be ready to dispose of the waste. Simply hook your RV up to the dump station and toggle the black tank valve to the “open” position.


Step 6: Close the Valve
Set the valve to close. Don’t forget, or you will be visiting this page again later.


Method Number Two: The Hands-On Approach

Tools that you will need

  • See-through Hose Connector
  • Sewer Hose
  • Water Hose
  • Strong Disposable Gloves
  • Power Drill


Step One: Put Some Gloves Before You Do Anything Else
I just saw a YouTube video of someone demonstrating how to properly unplug your RV, and I was horrified to see that he did not use gloves. Do not make that mistake. Your black water tank is filled with everything that your body decided that it didn’t want. Making contact with a bunch of festering excretions is the last thing that you should be doing. Please take the proper precautions.


Step Two: Attach the Clear Hose Connector
You will need to see how the water and waste are flowing, so you will need to attach a clear hose connector the exit pipe for the black water tank.


Step Three: Drill a Hole into the Clear Connector

I realize it can be a little disconcerting to drill into your new connector, but it needs to be done to create an access point for the water hose. Use a drill bit that is as close to the size of the water hose as possible. Any extra room will create a space where the waste that is being flushed out can escape, and take my word that you really don’t want that.


When drilling the hole, try to angle the drill towards the black water hose access point. Trying to get the water hose all the way up into the black water tank can be really frustrating, so you want to make it as easy as possible to snake the water hose all the way up into the tank.


Step Four: Snake the Water Hose up into the Black Water Tank

Using the drilled access point, direct the water hose into the black water tank.


Step Five: Turn the Water On

Once the water line is all the way up into the black sewer tank, turn the water on. There might be an…obstruction if the water doesn’t immediately start flowing. Wait about a minute for the water to do its thing. If there still isn’t a flow then you might need to readjust the water line.

The clear straight hose will allow you to see what is going on

Thanks to the clear piping, you will be able to tell if the water is flowing or not. If it isn’t, try re-adjusting the water line. Turn the water off, pull the water line a little bit back, turn the water turn. Try it again. If it still isn’t working, turn the water off and re-adjust the line again. It is a repetitive process, but it gets the job done.

Eventually, the water should start flowing, and you and the RV can both sigh in relief. If you are still having trouble, it might be useful to approach this problem from the other end. Sometimes, the pipe is actually clogged rather than being blocked at the endpoint. If this is the case, then simply sending water through the toilet and into the pipes to dislodge the obstruction. Be careful, you don’t want anything shooting back towards you.


Closing Thoughts and Preventative Maintenance

That should do it. Between the first and second method, that should take care of any clogs that are causing you problems. Make sure to toggle the black water tank closed, and you might want to consider adding some RV probiotic treatments such as Happy Camper to your list of routine maintenance. Like the Unique Tank Cleaner product, it is made to liquify the feces within the tank. That will keep any pyramid buildup from taking place. Also, it has the added benefit of stopping the bad odors that can sometimes take root. Okay, that’s it. Have a great day, and good luck on cleaning out that tank.

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