How To Stop A Toto Toilet From Hissing

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Toto toilets are renowned to be top-of-the-line appliances that frequently include luxurious features not found in standard toilets. They have advantages over their competitors, such as having a more powerful flush, quieter flush and refill noise, and typically less need for maintenance compared to standard brands.

Even such a high-end brand, however, would occasionally encounter some issues, such as having hissing sounds upon flushing. No need to worry though! We have researched  this topic thoroughly and made a simple guide on how to solve this issue.

Follow the steps below and the hissing noises on a Toto toilet should be gone immediately:

  1. Stop the supply of water to the toilet.
  2. Purge the toilet tank of water.
  3. Detach the water supply hose from the fill valve.
  4. Remove the top plastic cover.
  5. Remove the float valve mechanism.
  6. Take off the defective fill valve cap.
  7. Replace the faulty cap with a new one.
  8. Reassemble the fill valve.
  9. Reconnect the water supply hose.
  10. Open the water supply and verify the results.

We understand that hearing such noise frequently can be annoying. So in the following sections, we will be guiding you step by step on how to fix this issue. Keep reading as we will also discuss other relevant information that may be of use to you. 

An interior of the modern transparent public toilet, How To Stop A Toto Toilet From Hissing

Stopping Toto Toilet From Hissing

Toto is known to be one of the leading brands of bathroom appliances, with toilets being one of their best products. No matter how advanced or well-built the toilets are, though, occasional issues arise due to various causes.

One of these, according to members of an online plumbing forum, is the hissing that may occur due to degradation of the fill valve cap over time.

A leak can occur due to the imperfect seal, causing water to continue to trickle out of the fill valve, which produces hissing noises. The part that's necessary to fix the issue is a new replacement cap for the fill valve.

The following steps can be done to replace the cap and address this issue:

1. Stop The Supply Of Water To The Toilet

Hand turning a water shutoff valve mounted to a wall next to a toilet

The water supply to the toilet must be turned off first. This stops water from being wasted needlessly while attempting to solve the problem.

2. Purge The Toilet Tank Of Water

Purge the remaining water in the tank by flushing. This will allow for ease in checking and fixing possible defects in the assembly.

3. Detach Water Supply Hose From The Fill Valve

The supply hose is attached to the fill valve at the side of its plastic top cover. The hose must be removed first so that you can remove the plastic top cover of the fill valve.

4. Remove The Top Plastic Cover

You can remove the top cover upon detaching the hose from the fill valve. Simply pull the cover from the fill valve, and it should be removed without a hitch.

5. Remove The Float Valve Mechanism

Hand is fixing a toilet cistern at home

Upon removing the cover, you will immediately see a float valve mechanism on top. This mechanism is responsible for stopping the flow of water when the water reaches a certain height in the tank.

Remove it by pinching the sides of the mechanism attached at the top and then pulling it away.

6. Remove The Faulty Fill Valve Cap

New flushing mechanism to replace the damaged one

The fill valve cap usually degrades over time. Sediment or debris may accumulate on it, and long-term exposure to hard water may thin it down such that it won’t form a perfect seal anymore.

The fill valve cap can be removed by twisting it counterclockwise and then pulling it up from the fill valve assembly.

7. Replace The Faulty Fill Valve Cap With The New One

You can now replace the faulty fill valve cap with the new one prepared beforehand. It is recommended to choose known brands that are compatible with your Toto toilet since they will last longer compared to cheaper alternatives.

Replacement caps that are from Toto or Korky will work well. Put the replacement cap inside the valve assembly then turn it clockwise to secure it in place.

Check out this Korky replacement cap on Amazon.

8. Reassemble The Fill Valve Enclosure

Reattach the float valve mechanism on top of the replacement cap. Make sure that it is attached correctly before putting the top cover back on.

9. Reconnect The Water Supply Hose

Reconnect the fill valve to the water supply hose. To ensure that there won't be any leaks, make sure it is attached correctly.

10. Open The Water Supply And Verify the Results

Restore the flow of water to the toilet. Check if the hissing noise ca still be heard. If not, then congratulations! The issue with your Toto toilet is now fixed.

If the problem is still not resolved, the entire fill valve assembly may need to be replaced. If this does not resolve the problem, it may be necessary to seek expert assistance.

The cause of the problem may be with your water supply line, and you'll need the assistance of a licensed plumber to address the issue.

Why Does My Fill Valve Keep Running?

An overhead view of the plumbing inside a toilet bowl flush tank

The fill valve is responsible for replacing the water that is lost from the tank when flushing. It fills the tank until a certain height is reached.

So if the fill valve is continuously running, it means that it is unable to reach the max water level necessary.

When this happens, it is usually because the water level setting of the fill valve is higher than the overflow tube in the toilet tank, allowing for water to be continuously drained and unable to reach the desired water level height.

How Do You Adjust A Toto Fill Valve?

The continuous running of the fill valve is another common issue with toilets. This happens when the setting for the max water level of the fill valve is higher than the overflow tube of the tank, allowing for water to continuously overflow into the bowl.

This can be easily solved by adjusting the fill valve so that its max water level is lower than the height of the overflow tube.

First, close the water supply into the toilet. Then purge the remaining water from the tank. You can then see an indicator on the outer shell of the fill valve that tells you what is the max water level for the tank currently.

You can adjust the water level by either raising or lowering the fill valve. Turn the tube of the fill valve counterclockwise to unlock it.

Then adjust the height of the fill valve such that its max water level indicator is slightly lower than the overflow tube. Then turn it back clockwise to lock the fill valve in place at the chosen height.

Turn the water supply back on and check if the problem is resolved. If the water is still being continuously drained, then the problem may be the flapper valve that shuts off the passage between the toilet tank and the bowl.

This may then need to be replaced to ensure a proper seal between the tank and the bowl.

How To Know Which Toto Toilet You Have

A visitor takes a look of TOTO washlets at the TOTO booth

Knowing the exact model of your Toto toilet is important information, especially when you will be looking for replacement parts or even for warranty and service purposes. This information can be obtained inside the water tank of your Toto toilet.

The model number can be found either stamped or engraved on the walls of the tank. Sometimes it is underneath the lid of the tank itself. The model number is composed of a set of letters with a three-digit number at the end.

What Is The Warranty On Toto Toilets?

Toto provides a 3-year warranty from the date of purchase on their toilet products. Only Toto toilets purchased and installed in America are covered by the warranty.

The warranty covers the repair and possible replacement of the unit or only the damaged parts as long as the toilet was installed and used according to their instructions.

This warranty serves as a huge help, especially if your Toto toilet is still fairly new. You can contact Toto directly via their contact numbers at their website for warranty concerns.

In Closing

Hissing sounds from your Toto toilet can be annoying, but it is usually a simple problem to solve in a number of steps. We hope the detailed discussion in this post has been of help in solving this Toto toilet issue as well as providing insight on other concerns.

If you enjoyed reading this article, check out the related posts below!

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