Why Thetford RV Toilet Won’t Stop Running & How to Fix It?

In an RV or recreational vehicle, there are numerous problems that a user has to face. Among them, Thetford RV toilet won’t stop running is one of the most common ones. Like other RV equipment, a toilet can also have some issues like that. 

The most common reason for the toilet to keep running is a damaged water valve. It could also happen because of a faulty flapper chain or a clogged flush lever. 

I know these issues can be very disappointing when they are not properly acquainted. But fortunately, these problems are quite handy to deal with. So, let’s see what to do when the Thetford RV toilet keeps running.


What Causes Thetford RV Toilet Won’t Stop Running? 

Several reasons will cause a Thetford RVtoilet keeps running issues. Some of the major causes of this problem are the following: 

Bad Flapper 

One of the most common causes of why Thetford RV toilet won’t stop running is a bad flapper. A flapper is an important part of the toilet that allows the water to flow from the tank to the toilet bowl.

A Thetford RV toilet flapper usually lasts between 2-5 years. After that, it needs to be replaced. Because it can be clogged or worn out because of regular usage. So, if the flapper becomes clogged or too old, it can cause the toilet to run constantly. 

In this case, I found the flapper to be replaced to work well. Moreover, it isn’t so expensive. It may cost between $110 and $200. The labor cost will be around $50, while a new toilet flapper will cost between $60 and $120. 

Damaged Flush Button

The flash button of a Thetford RV toilet is a metal part of the toilet. So, it can be corroded over time. Once the flash button is damaged, it may let the bathroom keep running.

To fix this issue, I should always prefer replacing the button. Replacing the flash button is also quite simple to do. I can unscrew the button by hand and replace it with a compatible one. 

On average, the replacement cost of a corroded Thetford RV toilet flush button can be between $75 and $100. The parts are priced between $15.99 and $80 when the labor cost is around $55.

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Broken Flapper Chain 

Another cause of a Thetford RV toilet won’t stop running problems is a broken or rusty flapper chain. The flapper chain in a toilet is a part of metal that is connected to the toilet lever. It allows the flapper to keep open and enter more water into the toilet bowl for better flushing. 

But this metal element tends to be rusted or broken due to regular usage and poor mechanism. It can often be disconnected from the toilet lever. If it is just disconnected, a simple reattachment of the chain to the flush lever will fix the problem. But if it becomes broken or corroded, it must be replaced on time. 

The average cost of replacing a bad flapper chain in a Thetford RV toilet is estimated between $55 and $75. Labor costs will be around $50 and a new flapper chain will be priced between $7 and $12.  

Faulty Fill Valve 

A faulty fill valve is another notable cause of why a Thetford RV toilet keeps running. The fill valve in a toilet allows the water to enter the tank and fill the tank with water.

It is a complex mechanism and it can be damaged anytime. Also, it tends to wear out over time. In such cases, it may create leaks in different parts of the Thetford toilet and cause won’t stop problems. The replacement of the fill valve will be the first and foremost way to fix this problem. 

In general, the replacement cost of a faulty fill valve is estimated between $75 and $200. The parts will cost between $10 and $30 when the labor cost is between $50 and $120 per hour.

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Damaged Flush Valve 

If the flush valve is loose or gets too old, it will cause the Thetford RV toilet to not stop running issues. The flush valve is a part of the toilet that lets the water blow into the toilet bowl. 

When it is broken or corroded, it results in different problems like unnecessary sounds coming from the tank or the toilet keeps running for longer.  So, the only fix will be replacing the damaged flush valve. 

To replace a Thetford RV toilet flush valve, it may cost anywhere between $75 and $200. Here, the repair charge will be between $50 and $100, while the new parts will cost between $25-$150.

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How to Prevent Thetford RV Toilet Keeps Running? 

While enjoying an outdoor vacation with my thetford rv, dealing with various rv problems was very tricky and annoying for me. Especially, facing a malfunctioning RV toilet. So, I guess it’s better to be alert about the condition of the toilet and ensure that it is properly maintained.

  • First of all, the different parts of the toilet and their joints must be cleaned regularly. Because, if they become clogged, they will cause the toilet to not stop running.
  • The water level will always sit just under the overflow tube.
  • Make sure that the float tube is properly attached to the fill valve.
  • The flush valve, flapper valve, and fill valve should be checked regularly to see if they need to be replaced.

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There are different topics related to the Thetford RV toilet that won’t stop running. So, here are some of them:

How do you know if the flash valve is broken? 

The most common cause of a broken flash valve is that the toilet will run intermittently. Some of the other possible causes may include poor flushing power, getting unusual sounds, and water moving slowly inside the bowl. 

Does a Thetford RV toilet ghost flushing increase your water bill? 

The simple answer to this question is YES. Typically, it will waste more than 200 gallons of water per day than the normal flushing uses. So, ghost or phantom flushing will increase the water bill. 

Why does my Thetford RV toilet run randomly?  

If the Thetford RV toilet runs even if it is not being used, it is usually having a faulty toilet flapper. It also occurs because of a float tube, broken toilet chain, or damaged water valve. 

What is a ghost flashing on a Thetford RV toilet? 

When there is a sound like ‘flushed’ from the back of the toilet tank, it is called a ghost flashing on a Thetford RV toilet. It happens when the water level drops or there is leakage inside the tank. 


Typically the Thetford RV toilets have simple mechanisms and so troubleshooting for these toilets is also simple. I experienced it when I was unable to get professional help. All I need to fix the Thetford RV toilet won’t stop-running problems are a few pieces of equipment and some free moments.

But there are also some anticipatory things that I must be aware of to keep the toilet in good condition. This will save money from wasting on different requirements. It is also necessary to notice the source of the problem to avoid further damage. 

The easiest way to detect a damaged flush valve and a broken float tube or toilet chain is by mixing some food color into the water inside the tank. Then see if the coloring water is blowing inside the bowl.

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