Toilet is hissing, humming or whisteling: how to fix it NOW

It is always important to check what is going on when your toilet is making weird noises. A hissing sound can indicate that the toilet tank is being filled and is quite normal. If the sound keeps appearing for longer than a minute, it can indicate that there is an issue and something that needs to be checked. The most common issues are problems with the refill valve and flapper.  Fixing the flapper is often quite straightforward. Replacing a flush valve can be more work. Let’s dive in.


Before we start, we have to close the water supply. This is done by closing the valve next to the toilet. If there is no valve, we will have to close the main water supply. Water is under a lot of pressure and it can leak if you open up the toilet. To make sure that we don’t have water damage, it is best to avoid this by closing the valve. Once this is done, we can flush to get the water out of the toilet tank. It is always a good idea to have a bucket and some paper nearby as toilets can leak water if something breaks.

Let’s get the core issue fixed.   

What is a Flapper in a toilet?

A flapper is a valve found at the bottom of most toilets. It is part of the toilet tank. Flappers are usually plastic or rubber. If you flush, you push the flapper up and the water pours into the toilet bowl. These parts are generally quite cheap to replace but it can take some work as you have to remove other parts of the toilet as well.  We have discussed this part in more detail here.

How to Fix a Hissing Flapper Valve

We will have to open up the toilet tank to get access to the flapper. For a standing toilet this is quite straightforward as you just lift the lid of the toilet tank. For a hanging toilet, it can involve more work as you have to remove the flush panel. This is generally done by lifting it up. You might have to remove some additional parts before you get access to the flapper.

In a standing toilet, the flapper is connected with a chain. Check if the chain is working properly. It is also possible that the flapper is dirty and that cleaning fixes the issue. If that doesn’t work, we will have to replace the toilet flapper. This is quite easy in itself but you might have to remove quite a lot of parts of the toilets to get access to it in some toilets. 

In a hanging toilet, the toilet flapper is generally part of a plastic item. You can unclick it from the toilet tank. There is a rubber ring on the bottom. You can turn the ring around and see if this fixes the issue. You can also install a new rubber ring to see if this helps. If these options don’t work, you will have to replace this flush valve part. Let’s examine how this is done below.

What is a flush Valve in a toilet?

A flush valve is located at the bottom of the toilet tank. It controls how much water goes into the tank when someone flushes the toilet. It is connected with the flapper. This piece can harden or break over time. It is more work to get this replaced bus is doable.  You will need to know the model number of your toilet to get the correct part. If you aren’t sure, you can send a picture of your toilet to its manufacturer of it. Before you close it, you can test it to see if it is fixed now. 

How to Fix a hissing Refill Valve

A refill valve can crack over time and needs to be replaced. 

If you have to replace this part, you can unclick it in a standing toilet. We will have to detach the water supply line. This is generally done by turning the nut that connects to the toilet. Once this is done, we will have to use pliers to loosen the nut that holds the flush valve. Some water might leak so have a bucket nearby. Pull out the refill valve and install a new one.

You will need to know the model number to find a replacement part. Once you have the correct part, you can lock it in place with the nut and connect the other pieces. Open the water valve to test the new installation.

In a hanging toilet, you have to unclick the plastic part from the toilet. It is typically in the left part of the toilet tank. Installing a new one is quite easy as you just have to click it in place and you are done with it.

Once this is done, we can open the water supply to see if the hissing sound has been fixed. If it has, we can close the toilet tank and pad ourselves on the back.

To conclude, we can state that a hissing toilet can indicate problems with the toilet flapper or toilet refill valve. These are moving parts and they can break down over time. Fixing the toilet refill valve is quite easy. The flapper can be more work in older toilets. A hissing sound can also indicate a small water leak so you might check around the toilet to see if your feel or see a wet spot. A nut might have to be tightened or a water pipe replaced. We have discussed how a leaking pipe can be fixed HERE.

While you are working in the toilet tank, it can also be a great moment to clean it. This can be done with a cloth and brush. Most people don’t clean their toilet tanks and dirt can collect in them over the years. This can create problems with your toilet so giving it a quick wipe can do wonders. 

Finally, it can also indicate that some air has gotten into your water pipes. This can indicate an improper installation or degrading pipes. These problems are harder to fix and you might want to call a plumber to get help with this. In some instances, it can be a good idea to install a new toilet as it can indicate that it is reaching the end of its lifetime. There can be a lot of issues after each other if you have an older toilet. Toilets generally last 10-15 years. A leaking toilet can cause a lot of damage so it can be necessary to get it replaced once it has reached this age.