RV Toilet Won’t Flush – 7 Reasons & How to Fix It

rv toilet wont flush

If your RV toilet won’t flush as you are dealing with a malfunctioning toilet, you’re probably in a messy and unpleasant situation during your RVing adventure.

While using a plunger to push the wastes down the black water tank might be a temporary solution, identifying the root cause should help you institute the correct fix.

So, what causes an RV toilet not flushing water? More importantly, how do you address such an issue? This article answers these riddles so you can return to a more pleasant RVing adventure.

Please read on.

Common Reasons for RV Toilet Flush Failure


An RV toilet not flushing correctly can be attributed to various reasons, some of which might be easily overlooked. So, what causes your RV commode to not function as expected?

1. No water in the tank


Don’t laugh, but an empty freshwater tank might explain why your RV toilet isn’t flushing. It’s not getting water from the reservoir to flush the toilet’s contents.

2. Issues with the water pump


Even if there’s water in the freshwater reservoir, your RV toilet will refuse to flush if the water pump isn’t working. Little or no water pressure can leave the RV toilet dry and make waste disposal almost impossible.

Or, it’s possible you forgot to turn on the RV water pump.

3. A stuck or damaged flapper


Many RV owners find this to be the cause of why an RV toilet valve won’t open. The flapper or ball valve, usually made of rubber, can weaken and deteriorate over time. It could dry up and crack or fail altogether.

The ball valve allows water from the freshwater reservoir to enter the bowl and flush the contents to the black water compartment by opening the seal. Hence, a stuck flapper might explain why the water won’t go down.

4. Water line obstructions


We mentioned a freshwater tank supplies water to the RV toilet for flushing. There are flexible pipes between these components for the water to pass through.

Unfortunately, these plumbing fixtures can clog, causing various RV toilet problems. Kinks can also reduce water pressure and flow to the toilet, making flushing more challenging than usual.

5. Waste pipe clogging


Besides the pipe that connects the RV toilet to the freshwater reservoir, there’s another tube linking the commode to the black water or waste tank.

Foreign objects like soap, thick paper, and cigarette butts tossed into the RV toilet bowl can accumulate in the waste pipe and reduce its diameter.

This event prevents the RV toilet from effectively flushing because it’s clogged from top (between the black water tank’s inlet port and the waste pipe’s lower segment).

6. Black water tank full with waste


Black water tanks or RV waste reservoirs can accommodate 15 to 60-plus gallons of human waste. Hence, they require frequent emptying into designated waste management facilities (i.e., RV parks, rest stops, municipal septic tanks, and gas stations).

Unfortunately, some RV owners tend to forget this task. And it would explain why it’s challenging to flush RV toilet units.

It’s essential to understand that RV toilets operate as a closed system. If the terminal component (the black water tank) is already full, there’s a likelihood that the toilet won’t flush properly, and there’s an increased risk of the waste backing up into the RV toilet.

7. Incorrect RV toilet usage


Here’s another often-overlooked reason why an RV toilet won’t drain as effectively as it should.

The ideal RV toilet operation involves three steps:

  • Depress the RV toilet foot pedal lightly to allow water from the reservoir to enter the bowl.
  • Press the lever further down to fill the toilet with more water.
  • Push the pedal to the hilt to open the flapper and drain the toilet.

So, if you don’t observe this procedure, there’s a chance your motorhome toilet won’t flush properly.

Troubleshooting RV Toilet Flushing Issues

Knowing what causes your RV toilet to not flush properly brings us closer to fixing the problem. Let’s look at effective troubleshooting steps to resolve these issues:

1. Check if there’s water in the freshwater reservoir


Modern RVs feature a user control panel for monitoring the vehicle’s holding tanks. For example, Forest River has a colorful screen that displays the current levels of the freshwater, greywater, and blackwater reservoirs.

  • Refer to the manual: Consult your RV’s manual to see how to determine the water tank level using the control panel. Be cautious, as the water tank sensor could also fail, producing erroneous readings.
  • Inspect water pressure: If there’s water in the tank but the pressure is insufficient, try connecting the RV toilet to a different water source. Alternatively, you can pump the water line connected to the RV toilet.

2. Check the water pump


An RV toilet that doesn’t flush with force might indicate a problematic pump. Look for these tell-tale signs of a bad RV water pump:

  • Growling noise
  • Excessive shaking or vibrations
  • Loud banging sounds in the walls
  • Unexplained random cycling

In the worst cases, you won’t hear a sound coming from the pump.

However, before you entertain a defective water pump, you might want to check the power button if it’s switched on. Electricity to the water pump might also be problematic. So, we recommend checking these items before concluding that the RV toilet stopped up because of a defective pump.

Otherwise, you must replace the water pump with the correct unit.

3. Inspect the flapper


Try moving the flapper and see if you can get it unstuck. Remove and inspect the ball valve or flapper for signs of deterioration (i.e., brittle or cracked) or damage. A replacement is necessary if the flapper is beyond repair.

4. Assess the RV toilet water line


Look for the flexible pipe running to the RV toilet from the back. See if there are kinks and straighten the pipe. You might want to remove the hose from its connection and check for obstructions.

5. Unclog the RV toilet


You have several options to unclog a camper toilet:

  • The easiest method is to pour boiling water into the RV toilet and leave it overnight.
  • Alternatively, you can use a clog-removing agent and drive your RV for several hours to dissolve the materials clogging the waste pipe.
  • You can also use a toilet wand, plunger, or ice cubes.
  • The last method requires filling the RV toilet with water about a third full before dumping the ice cubes. You then drive around to soften whatever is clogging the toilet.

6. Empty the waste tank


Check your RV’s black water level monitor and see if it’s full. Drive to the nearest RV waste management facility and empty the waste tank. Please don’t forget to clean the reservoir before returning to its compartment.

7. Flush the RV toilet twice


This troubleshooting step will determine if you’ve been using the RV toilet correctly or not. Incorrect RV toilet operation is the likely culprit if you notice the toilet’s water level is significantly lower after flushing it for the second time.


Diagnosing the reason why an RV toilet won’t flush can be a challenging task. Although we offer the most plausible explanations for such a problem, we cannot discount the possibility of other causes.

Hence, if none of these causes explain why your RV commode doesn’t flush, it’s often wise to consult a licensed RV technician. However, we implore you to at least troubleshoot the problem. The steps are easy to execute, and you can complete the problem identification and troubleshooting in minutes.

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