Toilet Makes Hissing Sound: 7 Easy Ways To Fix It Now

Isn’t it annoying and even troublesome when your toilet makes a hissing sound?

These common toilet noises can also be a nuisance if neighbors share the same wall.

In addition to the annoying spooky sounds, these Common Toilet Troubles may result in wasting water.

There are different parts of a toilet that may emit this hissing sound.

So typically, the fix relies on determining the exact source.

Luckily, determining and fixing the culprit is a manageable task in many cases.  

If you have the same problem with your toilet, we are here.

We’ll share the common reasons behind this problem.

Moreover, we’ll widely discuss the best fixes and troubleshooting techniques.

Why Does Your Toilet Make a Hissing Sound?

The most common cause behind this annoying trouble is having air or water constantly moving from the water flow lines into the toilet tank.

In other cases, damage to the toilet flush chain prevents it from performing its primary function.

Subsequently, the water will keep passing out from the tank.

A clogged water valve is another common cause of permanent hissing in the toilet.

The valve may become partially blocked by sediments and debris, which significantly increases water pressure.

Then, water will be forced out as small leaks, making a disturbing hissing sound. 

It is time to shed more light on these reasons without further ado. 

1. Cracked Flush Chain 

This chain links the flushing handle and the toilet flapper valve in the most common toilet types

A functional chain allows these two components to work accordingly until a flushing cycle is complete.

A damaged chain won’t allow the tank to fill adequately.

Eventually, the water will leak in a narrow stream into the toilet, causing the funky toilet noise.

Inspect the chain for damage to evaluate its condition.

Sometimes, it is not broken or damaged but might be the wrong size

2. Clogged Inlet Water Valve

In all toilets, inlet valves allow water to flow into the cistern until it is filled.

This way, your toilet tank is ready for the upcoming flush.

As with any valve in the plumping world, it can get clogged with debris and sediment particles.

This way, the malfunctioning valve contributes to the strange noises from the toilet.  

3. Leaky Toilet Tank

A cracked tank commonly happens with age.

Also, it might crack with a heavy impact.

Regardless of the cause, this problem will always lead to unsettling noise from the toilet.

The real problem with cracked tanks is that they keep getting bigger.

So, the leaks will become stronger and the noises will become even more disturbing. 

4. Dirty Flapper Valve 

The flap valve empties the tank when the toilet is flushed. 

Whenever you flush, the valve opens, allowing all the water to leave the tank.

This component may come in different colors and be made of various materials.

The most common types in the market are either plastic or silicone.

Rubber flappers are also found but on a smaller scale. 

This valve becomes blocked with dirt particles, sediments, mold and even sludge.

An excessively clogged valve will let some water into the bowl without any need.

This scenario increases the hissing from the toilet issue.

5. Faulty Flush Valve 

As the name suggests, this valve allows the water to gush into the toilet bowl with every flush. 

The flush valve assembly is typically located inside the cistern.

So, it does the opposite task of the refill valve.

You can ensure there is a problem with this component when your toilet constantly runs. 

A damaged flush valve tube leads to the common toilet noise complaint. 

6. Defective Float Valve

A float valve or a ball cock unit are different names for the same component.

In all instances, a tank’s float allows the water to fill the tank without overfilling. 

When the tank refills, you will notice the float rises along with the filled water.

This valve is designed to let the water reach the set level otherwise, the water will overflow. 

A faulty float valve won’t turn off the water flow once the tank is filled.

This will also lead to water leaking between the flapper and the seal; eventually, you will hear the annoying sound from the toilet bowl. 

7. Improper Water Supply

Uneven or insufficient water supply reaching the toilet may cause the gurgling noise.

The noise may become more apparent every time the tank refills.

Usually, a weak water supply affects the power of the flush. 

How to Fix a Toilet Making a Hissing Sound?

The multiple causes of this problem may imply you need an emergency toilet repair.

However, the good news is you can DIY troubleshoot most of them.

Generally, there is little effort or tools required.

Just bring an open wrench and a pair of pliers for removing and reinstalling the toilet components.

Also, a screwdriver and a small plastic is required to dispose of any debris, sludges or clogging you might come across. 

1. Replace the Flush Chain   

Fortunately, a replacement flush chain is easy to get.

It is also cheap and won’t cost you over $3.

A broken chain is unfixable; you can, however, adjust its length to make it a perfect fit as a link between the flapper and the flushing handle. 

When you work on replacing this chain, cut off the water supply from the toilet and empty the tank.

You should remove the toilet tank lid to reach this part or any relevant tank component.

When you install the new chain, keep it always in a straight position.

Also, make sure the chain is never too long or too short.

Install the chain in a way that does not make it trapped under another component or make it twisted or raise the flapper above the required level. 

2. Clean the Inlet Valve 

This valve’s cleaning is a simple task.

There aren’t many parts in the intake valve replacement kits because you need a screwdriver and a bin.

Within 10 minutes, you will be done with this task.

Repeat the same steps in replacing the chain.

You will find this valve at the bottom of the tank.

Then remove its cap and seal and rinse to remove any accumulated debris.

Place an inverted plastic cup over the valve and turn on the water again.

The water will force any stuck debris out of the valve.

The cup or bin will prevent water from spraying all over the place. 

If cleaning does not solve the problem, you might have to change the entire inlet valve assembly, including the seal.

3. Replace the Tank 

In most cases, replacing a cracked tank spares you huge waste of money and effort. 

Large cracks on old tanks are unfixable, no matter what. 

However, tiny cracks can be sealed using epoxy.

Generally, you can do it yourself, but sometimes it’s better to call a professional to fix these minor cracks.

Otherwise, replacing the damaged tank is the best approach in this case. 

4. Clean the Flapper Valve 

This simple cleaning task will only take a few minutes of your day.

Repeat the same routine that you did with the inlet valve assembly.

But this time, you must perfectly wipe the tank’s bottom until it dries completely.

Then take out the flapper to inspect its cleanliness. 

If it turns out to be unclean, use a non-scratch pad to scrub the stuck buildup.

Then use a piece of damp cloth to finish up the cleaning process.

Finally, reinstall the valve and make sure it is not cracked. 

5. Change a Bad Flush Valve

Replacing this value is not different from any other similar component.

You will repeat the above mentioned steps, but this time you will take the flush valve out of the tank’s bottom.

Then reinstall the new valve.

If you contact a licensed plumber to make this replacement, the whole thing will cost you an average of $150.

However, the replacement valve will cost you at most $20.

The extra cost covers the time of a professional plumber. 

Generally, flush valves are expected to last between 6 and 7 years.

So, they are somehow sturdy components.

These valves are made of hard plastic combined with a brass fitting.

6. Replace the Faulty Valve

Unfortunately, a malfunctioning ballcock valve can’t be fixed.

However, you should thoroughly inspect it to ensure it has become completely useless.

So, take the valve out and check in until you notice any tiny holes or punctures.

This is your cue to make the switch.

Install the new valve to fit the place of its predecessor perfectly.  

7. Adjust the Water Supply 

In general, adjusting the water supply is a simple task.

The issue will be simple to tackle as long as there is no blockage in the lines or pipes.

All it takes is to find the main supply valve connected to the tank and adjust it accordingly.

Make sure that the valve is set to the optimal level. 

It is time to talk to a professional if this does not make the hissing sound disappear.  

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