Why Is My Toilet Making A Hissing Sound?

Hissing is not a sound you want to hear from your toilet. Sure, maybe in a documentary on snakes, but not from your toilet, of all places. It conjures up horrific images of a snake taking a chomp out of you in your most vulnerable moment. 

Not a pleasant picture, to say the least. Lucky for you, the reasoning behind the sound is nowhere near as dramatic as that. Although the sound is disconcerting, the logic is pretty simple, and the fix can be even simpler.

Why Does My Toilet Sound Like It’s Hissing?

The snake-like hissing sound you hear from your toilet is due to air moving through the water line into the tank. Usually, you’ll notice the toilet hisses when you flush it. This is because excess water or air is moving through the water line into the tank when it should’ve been cut off. 

Alternatively, it might be because of hard water deposits or sediment particles that have settled in the valve and partially blocked the water flow into the tank. The result? Water pressure increases in the valve, forcing the water out in a narrow stream and causing the concerning hissing sound. 

How Do I Get My Toilet To Stop Hissing?

Bathroom Toilet

For the most part, fixing the hissing problem is straightforward. Even an amateur plumber could fix this one. If the prospect of tinkering with the toilet to fix the problem sends you into a tailspin, it’s probably best to have a professional plumber handle the fix. 

But, with a bit of time, you should be able to fix the problem pretty quickly.

Note: After each potential fix, make sure you turn the water back on and check if the problem still persists. If you fix the problem on the first try, there’s no point in continuing down the list. If that’s the case, go you!

Check The Fill Valve Or Float

The fill valve is a potential culprit of the issue, so let’s start by taking a peek there. First things first, turn off the water supply to the toilet. Generally, there’s a shut-off valve close to the wall, so turn that clockwise until it stops turning. Don’t force it to turn; just stop when you meet resistance. 

Now, empty the tank by flushing the toilet. While the water in the tank is clean, like what comes out of your faucet, it’ll make these next steps easier if you’re not working in an aquatic environment. 

Once the tank is empty (or mostly empty), remove the valve cap and valve seal. Look for debris on the seal, checking for little mineral deposits or sediment that could be causing the issue. If there’s visible debris, clean it with cleaning solutions specifically for mineral or calcium deposits

If you don’t have any special cleaners on hand, use vinegar and water to tackle the deposits. Vinegar is acidic, which helps cut through the troublesome deposits. 

Make sure you examine the entire mechanism while you have it out to verify they’re in decent condition. If they’re not, replace the whole thing (the mechanism, not the toilet). Additionally, look at the float while you’re at it. If it’s damaged, replace it as well. 

Check The Flapper

If everything checks out with the fill valve, examine the flapper. This could be the cause of the hissing sound, especially if it doesn’t sit right and continues allowing water to flow when it shouldn’t. 

Clean it with water (and vinegar if there are mineral deposits), then look for warping or misshapen parts. If you find irregularities, it could cause the flapper not to close well, which could be the problem. 

While you’re in there, check the chain to see if it’s damaged. If the length is wrong, it could hold the flapper up, allowing water to flow constantly. Replace it as necessary.

Toilet Repair

If you can’t find the exact parts you need at a local hardware store, check the manufacturer’s website. It’s best to take the parts out of the system and to the hardware store with you, as you’ll have a better chance of finding an exact match. 

However, if your efforts prove fruitless, you can always order the parts you need online from the manufacturer’s website. You’ll have to wait a few business days for shipping, so it’s not the most convenient option, but it might be your best bet. 

Replace The Inlet Valve Assembly

In some cases, the entire inlet valve assembly might be worn out. If that’s the case, you might need to replace the whole assembly. Every inlet valve varies slightly in design, so they come apart in different ways. 

Check the manufacturer’s website for directions on disassembling yours, then install the new ones using the manufacturer’s instructions. You can usually buy replacement assemblies from the manufacturer’s website, but you also might be able to find a match at your local hardware stores. 

Generally, inlet valve replacement kits include all the parts you need to install the valve, along with installation instructions and directions for adjusting the water level in the tank.  

Call A Plumber

Sometimes, you won’t be able to fix the problem by yourself. Perhaps you’re missing something, or the repair requires more in-depth work. Either way, it might be time to call a licensed plumber. 

While the hissing problem likely isn’t harming anything, it can rack up some impressive water bills. So, if you’ve done all you can and the problem persists, give a local plumber a call for help.

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