What to Do If Kohler Toilets Keep Running?

Maybe you are here after you have noticed that your Kohler toilet seems to run continuously, or at least, running goes on and off unexpectedly.
What to Do If Kohler Toilets Keep Running?

Your first instinct might be to reach for the phone to call a plumber or contact Kohler customer support, but hold on just a moment. In most cases, a constantly running toilet can be easily fixed with a bit of DIY knowledge. 

Here, we have made it easy for you to find all the possible causes and the ways of solution to the problem. Only when you’ve failed after applying these methods, which is often unlikely, should you consider calling a plumber or seeking professional assistance? So, before making that call, be sure to read and apply the methods outlined in this article. These are sure to help.        

How Toilet Flushing Works? 

Before you find out the cause of the Kohler toilet running spontaneously, you need to understand the flushing mechanism because it is, by and large, the problem related to flushing that allows it to happen. 

It is very simple. You initiate the flushing process when you press the button or the flushing handle. There is water in the tank, and a valve or seal known as a flapper stops the water from entering the bowl from the tank until you flush. 

A chain lever is connected to both the flushing handle and the flapper. When pressed, the flash handle raises the chain connecting both parts and exerts tension on the flapper, causing it to lift off the opening at the bottom of the tank. 

At that moment, the water from the tank quickly flows to the bowl through two main channels. Once the water in the tank has emptied into the bowl, the flapper or valve closes to stop the flow of water.

Why Does Your Kohler Toilet Keep Running? 

Multiple causes could trigger the ghost flushing phenomenon in a Kohler toilet. However, most of the root causes are likely related to problems within the tank. Toilet tanks hold water until the flush handle is pressed. 

When there is a leak inside the tank and flapper, the water can seep through the leak without the flapper valve being opened or lifted. The leak might be due to a damaged flapper valve or an improper gasket seal within the tank. Here are the potential causes of the problem. 

Damaged or Worn Flapper Valve

The Flapper valve is an essential part of toilet flush that regulates water inflow to the bowl. However, the flapper valve can wear or damage with time and use. Many factors, including the natural aging of the valve, can contribute to these issues.

For example, continuous use of drop-in chemical bowl cleaner can be harsh on the rubber-made flapper. Moreover, mildew, mold, or bacteria growth can cause the flapper to crack or no longer fit properly around the flush valve.

In the aftermath, the flapper can’t function properly to stop the tank water from entering the bowl. The tank’s water finds its way through the damaged or cracked seal, continuously seeping into the bowl even when a flush hasn’t been initiated.

That’s why replacing the flapper valve every 3 to 5 years is quintessential to avoid this situation. 

Worn or Calcium Buildup on the Gasket

Some Kohler toilets have a canister-style flush valve. In this type of toilet, a cylindrical or circular canister with a gasket or sealing ring at the bottom is lifted when flushing the toilet. The gasket at the canister’s base creates a watertight seal between the tank and the bowl. 

When the canister is lifted during a flush, water flows into the bowl. Apart from that, the gasket helps reseal the tank to prevent further water from entering.

When the gasket or sealing rink becomes subject to the buildup of calcium deposits and corrosion, the gasket can’t provide or create an effective seal. Thereby, the water from the tank finds ways to leak into the bowl during intervals between flushing cycles. This buildup on the gasket indicates mineral deposits in the water. 

Sometimes, the gasket can also be damaged or worn with use. If you see that the gasket is worn or torn, you have to replace the gasket. And replacing it is quite simple. The gasket is just a rubber seal ring, which you can easily remove and put a new one in place.

Sometimes, the flush valve seal may not sit or fit correctly or become twisted or deformed. This improper seating can result in water leakage.

Chain Mechanism Issues

The constant running of Kohler’s toilet might also originate from simple chain mechanism issues. You have to check the flush system with the lid open and see if everything is up and running smoothly. 

Sometimes, the chain becomes bent or kinked and doesn’t move as it should. The chain can also be affected by rust, which impedes the chain to function and move smoothly. Examine the entire mechanism carefully and ensure that everything is in good working condition.

Fill Valve Problem

The fill valve is responsible for controlling the water level in the tank and shutting off the flow of water once the tank reaches the target level. If the case is that the tank continues to be overfilled with water and the filling goes on without stopping, then the problem probably lies in the fill valve. 

The fill valve might also have some leaks in any part of it. You can inspect it by flushing the toilet with the lid open, and it may show some signs of a leak. Sometimes, the fill valve gets stuck because the arm is not rising properly, and you need to inspect it as well. 

The Float

A universal cause of the problem for all the toilets is the float not adjusted to proper height or functioning at all. An unadjusted float ball causes the water level in the tank to rise. The rising water level spills into the overflow tube, and the overflow tube is used to direct the excess water into the bowl and prevent the tank from overflowing. 

Consequently, the overflow tube will continue to funnel this excess water into the bowl, causing your toilet to add water to maintain that overly high water level. Therefore, the toilet tank continues running and makes a noise.

Float ball and fill valve mechanism addressing the issue of Kohler toilets continuously running.

If you’re dealing with a running Kohler toilet, you might also be interested in understanding why the toilet bubbles during a shower.

How to Fix the Kohler Running Toilet

No matter where the problem arises, you can tackle the situation by carefully understanding the cause and selecting the appropriate solution method. Here are some potential troubleshooting methods for the problem.

Replace the Flapper or Gasket

In the case of the flapper, there are several types of flapper valves, including the rubber, tank ball, or seat disk. Identify the right kind of flapper valve your toilet has, and then consider the size. There was a time when every toilet flapper had a universal dimension. Now, the size of the flapper varies from model to model. Regardless, the size of the flapper will be in the range of 2″ to 4″. 

If you know the model number of your Kohler toilet, it is even easier to find the right-sized flapper. You can look inside the toilet tank for the model number in case you don’t know. It can be under the lid or inside the walls of the tank. The same is true for the gasket seal. Moreover, you can bring the gasket seal to the supply store to purchase a similar one. 

Clean Gasket or Rubber Seal

If your Kohler toilet has a canister-style flush valve, it may be sealed with a rubber seal or gasket. Previously, we discussed how replacing this part might solve the problem. But, sometimes, you don’t even need to replace it. 

Sometimes, the calcium buildup around the gasket stops the gasket from sealing the tank properly. If you remove and clean the buildup around the gasket, the running and leaking issues will probably be gone after you reattach it under the canister.

Inspect the Water Supply Valve

Please take a look at the water supply valve and make sure it is fully open. Sometimes, the problem occurs just when the water supply valve stays closed or partially open. The water supply valve is responsible for providing water to the toilet tank. 

When it is closed or partially open, the tank can’t fill up. Consequently, the toilet’s fill valve will keep running because it’s unable to reach the desired water level.

Low Water Pressure 

If the issue is not resolved after the water supply valve is opened fully, the problem might originate from the low water pressure in the water supply. Lack of pressure in the water supply causes a constantly running toilet. 

When there isn’t enough water pressure, the fill valve may not receive an adequate flow of water to fill the tank to the proper level. Therefore, the fill valve will keep running to compensate for the lack of water. If the pressure is low, you may need to consult a plumber to resolve the problem. 

Adjust the Float

If the problem originates from the float ball not being adjusted to the right height, you must adjust the float. Set the float at a lower height than the overflow tube. You may find a tuning screw on the fill valve to regulate the water level height and the mark inside the tank. Adjust the water level accordingly and ensure it doesn’t reach the level of the overflow tube. 

Replace the Fill Valve

If you find any leaks in the fill valve or the tank doesn’t stop filling with water, then you might need to replace the fill valve. It is quite easy to replace a fill valve. Here is the step-by-step process of how you can do it:

  1. First, Turn off the water supply and disconnect it from the toilet. 
  2. Drain all the existing water in the toilet by flushing it thoroughly. Ensure that all the water from the tank is drained. You can also use a towel to remove any remaining moisture. 
  3. Open the water tank cover and locate the fill valve. Fill valves can be of many types. Identify the one in your Kohler toilet and find the right replacement that is compatible with your toilet tank. 
  4. Now remove the existing fill valve. It is normally connected via a nut to the toilet tank. You have to remove the nut by unscrewing or loosening it. Once the nut is removed, you can simply lift the fill valve without any pushback.
  5. Next, you have to install the new fill valve. You can carry the older one to the store to buy the exact compatible fill valve. 
  6. The Installation process is different for each model. You can achieve this by carefully reading the installation instructions provided with the new fill valve. 
  7. In most of the Kohler toilets, the process is to insert the new fill valve base into the place of the tank that was previously occupied by the older one. Press it down and lock it to the toilet by tightening the nut with a wrench. 
  8. When completely installing the new fill valve, it is important to adjust the height. The adjustment involves changing the height of the fill valve to ensure it perfectly fits your toilet. Keep in mind that the upper marking on the valve should never surpass or remain at the same level as the top of the overflow tube. In this case, you can follow the provided instructions. 
  9. Reconnect the water supply hose to the toilet and turn on the water supply as well. 

After replacing the fill valve of the Kohler toilet, the problem of constantly overfilling the tank and the toilet running might be resolved. 


It is important to take action immediately when you notice your toilet running non-stop or intermittently. You won’t want to be burdened with extra water bills for usage you never intended. That’s why that persistent, regular sound in your toilet should concern you. In this article, we’ve put forward a range of potential solutions to stop the constant running of your Kohler toilet. By carefully reading through this article, you should be well-equipped to resolve the issue on your own. However, if all your inspections and attempted solutions prove ineffective, feel free to reach out to the Kohler customer care center for expert assistance.

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