A hundred years ago, hearing the sound of hissing coming from the bathroom meant you needed to check the outhouse for snakes. Today, the hissing you hear is likely to be coming from your commode not shutting down after the tank is full. While this isn’t likely to result in a painful bite, your wallet is bound to experience shock at the increase in your water bill. Let’s explore the cause of your hissing toilet and what you can do to stop it.

Toilet Anatomy

Toilets are rather uncomplicated. Inside the tank are three parts, each with a specific function.

*Flush valve – This is in the middle of the tank and is used to open up the pipe that allows waste to be removed from the commode.

*Flapper – This is attached to the flush valve. When the flush valve is opened, the flapper is pulled upward, opening the draining hole.

*Fill valve – This is where fresh water enters the tank. As the water rises in the tank, a sinker that is attached to the fill valve floats upward. When it reaches a pre-determined point, the fill valve is shut off.

The concept is simple, but something can go wrong during any of the steps. The hissing sound you hear coming from your tank is most likely the sound of the fill valve not shutting off, but the cause isn’t always there.

What Can Go Wrong and How to Make it Right

There are three main reasons that can result in the fill valve not shutting off. These are the flapper, flapper chain and the float. Each is easy to fix, but you need to narrow it down to exactly which part is the cause of your hissing toilet.

Flapper – The flapper that is raised to allow water to exit the tank can become warped. When this happens, it doesn’t settle tightly over the drain hole, which causes water to continuously leak from the tank. As the water leaks out, the float lowers and this tells the fill valve to add more water.

Examine the flapper and make sure it is flat. Watch as it settles over the drain hole and see if it is placed correctly and provides a leakproof seal.  If it is wrinkled or otherwise not fitting, turn the water off to the tank, flush it and remove the the flapper. Take note of the brand of toilet you have and visit your local hardware store for a replacement.

Flapper chain – The flapper is attached to the flush lever of your toilet by a chain. If the chain isn’t the correct length, it can keep the flapper from settling correctly in position. If it is too short, the flapper won’t settle tight enough. If the chain is too long, it can find its way under the flapper, causing a gap to form and allow water to leak out. This causes the annoying hissing toilet syndrome.

If the chain appears to be too long or too short, simply reposition it where it is attached to the clip that holds it. This should solve the problem.

Float – The overflow on your toilet tank allows for a certain amount of water before it automatically starts draining through the overflow. The float that is attached to the fill valve reaches that pre-determined point and this is what tells it to shut the fill valve off. If the float is rising too high, water will drain through the overflow, causing the tank water level to lower and the fill valve to turn on.

You check for proper float level by taking note of where the overflow is located and measuring down approximately half an inch. If you see the float is rising above that level, you need to readjust it’s location on the fill valve so that it stops before it gets too high.

No More Hissy Fits

One of the three above fixes should have your hissing toilet happily quiet once again. If you have done all three and you still hear hissing coming from the toilet, you should call your local snake charmer…er…plumber and have him come and check things out.