How to Unclog an RV Toilet

You notice a foul odor in your campervan or trailer. Finding the source of that odor and fixing the problem must be a priority issue. More than likely, the source of that odor is the toilet. Toilets in campervans do become clogged, although the problem may not be apparent at the toilet. How do you diagnose and fix a campervan toilet that isn’t flushing?

Diagnosing a clogged campervan toilet can be a disagreeable task. If done systematically, the process can be much less disgusting and easier than you think.

  • Check the toilet.  
  • Check the Holding tank.  
  • Check the dump valve
  • Clear the pipes

To unclog your RV toilet, you can try using a plunger or a toilet auger. If these methods don’t work, you can try using a drain cleaner or a chemical drain opener. Be sure to follow the instructions on the product carefully. If all else fails, you may need to take your RV to a service center for professional assistance.

We’ll discuss the methods that can help you determine why your rv toilet water won’t go down and share advice to fix your toilet not flushing.

campervan toilet

Finding the Problem – Start at the Top

Finding the source of the problem with your campervan toilet may present a challenge. If your nose was the first indication of trouble, there is a good chance the problem is in the toilet itself. Therefore, the logical place to start is in the toilet.

flush valve rv

Examine the toilet to make sure there are no problems with the sealing valve or the flush mechanism.  Use the foot pedal to flush the toilet a few times. Some things to look for are:

  • A non-working flush valve. – If the flush valve at the bottom of the toilet doesn’t open and close fully, the flush valve may be your problem. You should also watch for adequate water flow in the bowl of the toilet when the flush valve foot pedal is depressed.
  • A flush valve that sticks and doesn’t close or open fully. – Operate the flush valve foot pedal several times and ensure that the valve at the bottom of the toilet bowl is opening and closing fully. Waste material or foreign objects can buildup and inhibit the full operation of the valve.
    If the flush valve doesn’t work, or it is sticking in a partially open position, that is a problem. If the flush valve is damaged, in most cases, the entire toilet must be replaced. If you suspect that your flush valve has problems, contact your RV dealership for more options.
  • A lack of water flow – Waste material in the toilet bowl that appears to be a clog may be the result of inadequate water flow into the toilet bowl when the flush valve operates. Press the flush valve several times to check the water flow into the toilet bowl.
  • Waste material in the bowl of the toilet or visible below the flush valve.

Water Flow – The Key to A Good Toilet Flush

water system rv

Without a good flow of water through the toilet bowl, it will not flush properly, and a pyramid plugs (see next section) will happen. If the water flow in your campervan toilet is slow or weak, check for these problems.

  • An empty water tank – Check your water tank.  Sensors and indicators can fail and may give inaccurate readings.  
  • A pump that is not turned on or not working – Some toilets require pressurized water to operate properly. If your water pump is not operating, the toilet will not flush effectively. Ensure that the water pump comes on when a tap opens or the flush valve on the toilet is activated.
  • Kinks or other obstructions in the water line to the toilet – Examine the water line that feeds the toilet flush valve.  If it is kinked or obstructed, the toilet may not get enough water flow or pressure to move waste out of the bowls and the black water tank.
  • A broken flush valve – Not only does the foot pedal on the flush valve operates the valve at the bottom of the toilet, but this valve also opens the water supply valve to allow water to flow into the toilet bowl. Without water flow, the waste material can buildup and clog the toilet
  • Keep your black tank closed – Indeed, having your black tank valve closed until it’s completely full allows the waste to slosh around. It won’t have the possibility to stick in your black tank. Once you open your valve to dump your waste, everything will flow out more easily thanks to the strong current created by the full tank.
    On the contrary, letting your valve open during normal operation will let the waste accumulate at the bottom of your flat black tank. Over time, it will solidify and pill up until you’re black water tank is clogged.
A man is emptying the RV sewer after camping. He is wearing gloves.
Keep your black tank closed and empty it once full.

RV toilets not flushing – The Easy Diagnosis

If there is waste material still in the toilet bowl after you flush, you should suspect water flow problems. However, there may be more subtle problems that are not visible from the top of the toilet. These could include 

  • Poor operating procedures – Many times, when traveling with children, you will encounter clogs in a campervan toilet because the younger ones forget to flush or use too much toilet paper. The waste material can harden and form clogs that prevent the flush valve from opening. 
  • A clog in the waste pipe that backs up into the toilet – The problem may not be in the toilet. Clogs can happen in the pipes below the toilet and allow waste material to build up enough to be visible in the toilet or just below the flush valve.
  • A full waste tank – Never discount the possibility of a full waste tank. Indicators and sensors are prone to failure as well and you can get false readings at the control panel. Before taking any other steps, dump your waste tanks and make sure they empty and rinsed.
  • A “pyramid plug” in the waste tank – The most susceptible to encountering a pyramid plug are RVs that stay for long periods of time on campgrounds with direct connection to their black water system. Waste material can pile up and eventually clog your black water tank. That’s why you should keep your black water tank closed and flush it when it’s full (see “Keep your black tank closed” previous point).

Dealing with Clogged RV toilets – Options and Solutions

The solutions and options to a clogged toilet in a campervan depend on the reasons for the clog. If you have followed the instructions and diagnosed the cause of the clog, you can decide on the best options and solutions.

Here’s a great video by The Fit RV showing you how a black water tank works:

Related Guide:
This Is How Portable Toilet Works

When the Flush Doesn’t Happen

If you have discovered that the problem is the flush system on your campervan toilet, one of these options may solve your problem.

  • Repair the toilet flush system – Many campervan toilets have flush valves that can be rebuilt or repaired. Check with the manufacturer of the toilet installed in your campervan for more information. 
  • Replace the toilet – Replacing a toilet in a campervan is not as involved as you might think. The fittings and attachments are standardized.  Your RV dealer can offer more advice, but, in most cases, installing a new toilet in a campervan is easily accomplished by the campervan owner.
Related Guides:
17 of the Best Camper Van Portable Toilet Setups You Need To See
These Campervan Toilet Ideas Will Blow Your Mind
Top 5 Best Cassette Toilets

There’s not Water

If water flow problems are the issue and you find that the water pump in your campervan is not performing properly, it is probably time for a new pump. Many campervan owners replace water pumps with no problems. Your RV dealer is your best source of advice on pumps and services.

If the pump is operating and there is a problem in the supply line to the toilet, the fix may be more involved. A clog in the supply line may be the problem. Damage to the supply line that inhibits the flow is another possibility.  

Often the supply lines run under the trailer or through walls or bulkheads. If this is the case, you may need the services of a trained RV technician to find and fix the problem

When the Water isn’t Going Down

If your flush system is working properly and the water isn’t going down after you went to the toilet, in the majority of the case it’s due to a pyramid clug (see previous point). The first thing to try is to use chemicals that are especially made to disintegrate all the waste in your black water tank.

It’s important to close your black water tank and wait at least 24 hours for the chemicals to produce the desired effect.

RV Toilet Treatment Drop-Ins, Breaks Down Waste And Tissue

Essential for RV Black Water Holding Tanks: Eliminates odors and helps break down waste and tissue in your RV's black water holding tank.

If you make a purchase, you support by allowing us to earn an affiliate commission (no added cost for you).

If this doesn’t work, you can try to manually clean your black water tank with a special outlet valve:

Valterra Flush King

You want to close the valve, fill your black tank with the connected hose and then open the valve again to get all the waste out. You can repeat the process until you see almost no waste going out. Depending on the amount of dirt there is, some people say it took them 10 times to have it completely clean.

Valterra Flush King™ 45 Degree Reverse Flush Valve Attachment for RV, Camper, Trailer

Breaks up plugged tank pipes and cleans tank, pipe, valve, and drain hose. Clear walls allow you to see when water is running clear

Universal Fit

If you make a purchase, you support by allowing us to earn an affiliate commission (no added cost for you).

Deeper into the Toilet System – Clogged Pipes

Larger campervans can have extensive waste pipe systems leading to the black water holding tank. Just like the drainpipes in your home, these pipes can clog. Removing clogs in drain systems on campervans is not difficult but does require some knowledge.

  • Do not use household drain cleaners – Household drain cleaning products are highly caustic or acidic and can seriously damage the drain system. Gaskets and seals in RV toilets are also at risk of damage if exposed to household drain cleaners. There are specialty products meant for RV’s.
  • Don’t Use Power Snakes – The typical powered drain snake used by plumbers is not safe to use on your campervan drains. The power snake can damage fittings and connections. If you must use a snake, a manual snake designed for RV drain systems is available.


Inevitably, you will experience a clog in your campervan drains system. It will happen much faster if you’re not taking care of your water system, and particularly if you let your black water tank valve open. However, the solutions to clogs in campervan drain systems are typically easy and quick. Don’t despair when you face a campervan toilet that refuses to flush. A little knowledge and some practical tips can help.

Leave a Comment