5 Kohler Canister Flush Valve Problems & Fixes

When it comes to toilet problems, a malfunctioning flush valve is among the most frustrating issues you could face. Most Kohler toilets use a canister flush valve known for powerful flush and reliability but strive to learn the fixes for Kohler canister flush valve problems should they arise.

Common problems stemming from a faulty Kohler canister flush valve are running toilet, leaking, stuck canister, and toilet hissing. Moreover, the toilet bowl water level can run low, toilet flushing on its own, and the valve could drop too quickly.

Kohler canister flush valve troubleshooting helps uncover the causes of the problem and guides you toward the right solution. Keep reading for the causes and fixes.

Kohler canister flush valve adjustment

Kohler Canister Flush Valve (Causes & Fixes)

 ProblemPossible CausesRecommended Fixes
1.  Kohler Canister Flush Valve keeps runningFaulty flapper valve Loose chain
Clogged valve
Loose or damaged flush handle
The water level is too high
Replace the flapper valve
Adjust the chain
Clean the canister flush valve to remove debris buildup
Tighten or replace the flush valve Reduce the level of water inside the tank
 2. LeakingDamaged seal
Dirty valve seat
Cracked flush valve housing
Worn-out canister
Replace the seal
Brush and wash the valve seat
Replace the flush valve housing
Install a new canister
 3. Stuck CanisterMineral buildup
Debris Damaged canister
Misaligned or loose parts
Clean the canister with water and vinegar
Flush the system
Replace the canister
Realign the canister and tighten loose parts
 4.Hissing ToiletWorn-out seal or flush valve
High water level
Replace the seal or the entire flush valve
Adjust the water level
 5. The Flush Valve Dropping Too QuicklyLoose canister seal Loose chain
Faulty flush valve
Adjust or replace the canister seal Adjust the chain
Replace the flush valve

1. Kohler Canister Flush Valve keeps running

A running toilet is among the most common toilet problems and is also costly, so fixing it is essential. However, before that, below are the possible reasons for a running Kohler canister flush valve.

a) Faulty Flapper Valve

This tiny rubber stopper sits on the flush valve and controls water flow into your toilet bowl. Water can flow nonstop if the flapper valve is damaged.

b) Loose Chain

If the chain joining the flapper valve and flush handle loosens, it can keep the valve from sealing well. The flapper valve must seal to prevent continuous water flow into your toilet bowl.

c) Clogged Valve

Your Kohler canister flush valve can clog for numerous reasons. For instance, hard water can cause mineral buildup, accumulating on the valve seat or the flapper, keeping it from sealing correctly.

A foreign object or debris can also get lodged in your toilet’s flush valve, keeping it from closing as well.

d) Loose Or Damaged Flush Handle

The flapper valve can also stop working correctly if your toilet’s handle is loose or damaged. This will let water flow into the bowl continuously.

e) Water Level Too High

A running toilet can also happen if you set the water level too high, channeling the water into the overflow tube.


  • Clean the valve thoroughly to remove any obstructions.
  • Tighten or replace the flush handle.
  • Adjust the water level to be at the recommended level, usually marked on a toilet tank’s interior.
  • Replace the faulty flapper valve.
  • Adjust the chain length so it has enough slack, thus allowing the flapper to close appropriately but not too much slack to prevent it from sealing tightly.

2. Leaking

Leakages associated with the Kohler canister flush valve can be attributed to various issues. So, if you experience this issue, check these causes.

a) The seal

A worn-out or damaged seal is the most common reason for a Kohler canister flush valve leaking. Remove the canister and inspect the gasket to check the seal.

b) The Valve Seat

The issue could be a dirty valve seat if the seal seems to be working just fine. The valve seat refers to the opening in the flush valve housing opening the canister seal sits against.

A properly working valve seat provides a tight seal. Unfortunately, over time, mineral deposits or debris accumulate on it, keeping it from sealing.  

c) Cracks

In addition, you should examine the flush valve housing for damage or cracks because it causes toilet issues like leaks. The housing holds the toilet’s flush valve assembly and forms a seal between the toilet bowl and the tank.

d) The Canister

You may be dealing with a damaged canister if none of the above steps resolves the issue. The canister can get warped or damaged, preventing it from sealing correctly.


  • Replace the seal with a new one if worn out or damaged. The Canister Flush Valve Seal- Impresa Replacement Rubber Seal for Toilet (View on Amazon) is an excellent choice because it is durable, easy to install, and made for most Kohler toilets. 
  • Clean the valve seat using a soft cloth or brush and a mild abrasive cleaner to scrub away any buildup gently.
  • Check whether the housing is damaged or cracked and replace it if necessary.
  • Change the faulty canister.
Kohler canister flush valve seal Replacement

3. Stuck Canister

A toilet canister controls water flow from your toilet’s tank into the bowl. It must work well, or else the flushing system will develop problems.

Unfortunately, the canister can get stuck for different reasons. Here are the common causes

i) Mineral Buildup

Since your toilet tank stores water, it shouldn’t be surprised when it develops mineral buildup due to hard water. However, the problem is that it can cause the canister to stick.

Consequently, the buildup can keep the canister from moving up and down smoothly, causing problems with the flushing system.

ii) Debris

Besides mineral buildup, debris such as dirt, sand, or small objects can inhibit the movement of the canister, causing the flushing system to malfunction.

iii) Damaged Or Worn Canister

The canister can also stick due to wear and tear or damage, which can happen because of a manufacturing defect or prolonged use.

iv) Misaligned or Loose Parts

Loose flushing system parts or a misaligned canister can also make the canister get stuck. This can result in poor flushing or continuous running. 


The solution for a stuck canister depends on the cause. If the problem is mineral buildup, clean the canister using water and vinegar.

On the other hand, flushing the tank system using water helps remove debris. However, a canister replacement may be necessary if damaged or worn out.

Additionally, align the canister if misaligned and tighten loose flushing parts.

4. Toilet Hissing

Your toilet can hiss due to problems with the Kohler canister flush valve. For example, a worn-out or loose seal can let water leak into the toilet bowl, causing a hissing sound.

In addition, excess water from setting the water level too high will flow into the toilet bowl, creating a hissing sound.


Inspect the water level and adjust it to the recommended level if set too high. In addition, replace the seal if worn out.

It would be best to examine the canister flush valve for wear and tear signs and overtightening. Depending on the issue’s severity, loosen it a bit or replace it.

5. The Kohler Canister Flush Valve Dropping Too Quickly

Your flush valve should not drop too quickly because that will lead to poor flushing because of insufficient water. However, multiple reasons can cause this problem, and you should know them and how to handle them should this issue arises.

For instance, the canister seal may be slightly loose, causing the water to leak out of the canister and making it drop too quickly. Furthermore, this problem can happen if the canister chain is loose.

The flush valve may also be damaged or worn out. In this case, the flush valve replacement is essential for proper function.


  • Adjust the canister seal to ensure it offers a tight seal or replace it if damaged.
  • Adjust the chain to the correct length- not too long or too short.
  • Replace your Kohler Canister flush valve (view on Amazon). This complete assembly featuring a tank-to-bowl gasket is designed for Kohler Cimarron toilets.

How To Adjust A Kohler Canister Flush Valve

Here are the steps to follow to adjust your Kohler Canister flush valve.

  1. Halt the water supply to your toilet temporarily through the shut-off valve, then take out the tank lid and put it in a safe space.
  2. Locate the canister flush valve. It is at the tank’s center and connected to the toilet handle by the chain.
  3. Adjust the chain length so that it has proper slack when the handle is at rest. The canister flush valve may drop too quickly if the chain is too loose. On the other hand, it may not let the canister close fully if too tight.
  4. Test the flush. After adjusting the chain length, flush your toilet to see if the canister valve operates properly. If the canister drops too quickly or doesn’t close completely, adjust the chain length further.
  5. Put the tank lid back, then open the shut-off valve to restore water flow.
Kohler canister flush valve repair

How Does Kohler Canister Flush Work?

Kohler canister flush functions using a canister at the tank’s bottom to hold the water needed for flushing. The lift wire or chain attached to the lever lifts the canister when you press the flush lever, causing the water to flow into the toilet bowl.

After that, the canister drops down to seal the opening, preventing water from continuing to flow into the bowl. The canister provides a better seal compared to flappers minimizing the chances of water leaking into the toilet bowl, preventing water waste and higher utility bills. 

In addition, the Kohler canister flush gives a more powerful and consistent flush than the traditional flapper flush. It also needs less maintenance and is quieter.

Summary of Kohler Canister Flush Valve Problems

To continue enjoying the powerful, efficient flushing provided by the Kohler canister flush valve, diagnose and fix the issues. While these problems can easily be fixed through a simple DIY project, some situations may need a professional touch. Nonetheless, refer to this Kohler canister flush valve troubleshooting guide when issues arise.

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