Toilet Is Making Hissing Sound When Flushing? (Fix It Now!)

When it comes to household issues, few are quite as frustrating as dealing with a malfunctioning toilet. There can be a plethora of issues with plumbing throughout the life of a home and dealing with your toilet is probably the last thing you want to address.

Perhaps you have been hearing a hissing sound, something akin to a loud snake, when you flush. What’s the problem there? Well, the most likely culprit is that the fill valve has either become blocked up or broken entirely. In some cases, you can get away with cleaning it. In others, you will need to replace the fill valve entirely.

Hearing a hissing noise emanating from the toilet may not be cause for dire concern but it certainly is not a pleasant noise. It sounds similar to a really big snake being vocal in your bathroom. But why is your toilet doing that in the first place?

Water pressure. The inlet water valve, also known as the fill valve, is typically the cause. Hard water deposits can and will build up over time. They settle into the valve and then block the flow of water going into the tank. That obstruction increases the water pressure within the valve.

That build-up of water pressure forces the water out through a narrower stream, which causes the hissing noise you hear as well as slow flushing. It won’t necessarily do damage to the toilet, but it definitely will not go away on its own.

It is important that you inspect the seal inside of the inlet valve cap. Make sure that there is no damage or warping, otherwise it will not seal properly. If you notice damage, that could potentially be the reason for the toilet hissing.

The good news is that replacing it is relatively easy. You can opt to go through the manufacturer for a new one. The easiest solution is to just take the old one to a local hardware store and find a new one that matches. All you have to do is put the new seal in place of the old one and the inlet valve assembly should work fine again.

So, you’ve tried flushing. You’ve tried replacing the valve seal. Still, the hissing continues. If you have gotten this far, it could be that the valve assembly needs replacing. The most likely reason is that hard water formed down in the lower part of the inlet valve assembly.

When that hard water deposit forms, the only way to resolve the issue is to completely replace the valve assembly. This can be something of a complicated fix. Unless you have experience with more complicated toilet repairs, this one may be best left to the professionals.

Unfortunately, hissing is not the only problem you may run into. There are a few different sounds to contend with. You may even run into something known as ghost flushing. These are all relatively normal and explainable. Even better, they all have solutions that you can implement to get rid of the issue.

In general, there are a few common causes. The aforementioned fill valve, a leaking toilet valve, or mineral buildup somewhere within the system.

This one tends to cause a few jumps. For whatever reason, right in the middle of the night, the ghost can seemingly flush on its own. The good news is that you don’t have a ghost problem and the actual explanation is a simple one.

A bad flapper. The most likely cause is that the water in the tank is slowly seeping out. The most likely source for the breach is an issue with the flapper. When the float gets down below a particular level, the water will switch on. Before you know it, it seems like the toilet is flushing on its own.

Inspecting and fixing. To find out if the flapper is the issue, it is as simple as using food dye. Give it about 30 minutes and look to see if any of that food coloring has made its way into the bowl. If you see color, replace the flapper.

The good news is that flappers are not only inexpensive to purchase, but they can be replaced by even the most novice of DIY types. Turn off the water, disconnect and remove the old flapper, and install the new flapper. It is as simple as that to replace.