If you listen closely, a hissing toilet is trying to tell you I need repair! Or Something’s wrong with your plumbing! In all seriousness, a hissing toilet isn’t something you can or should ignore. Even if it’s just an annoyance here and there, a hissing toilet can indicate faulty parts or even an underlying problem with your plumbing system.

Getting ahead of the issue will help prevent costly repairs or dangerous plumbing issues. Find out what might be causing spooky hisses from your toilet and how to fix it.

First, Identify What’s Causing the Hissing Toilet

A hissing toilet could result from many issues with the toilet or your plumbing system. To answer the question, “Why is my toilet making a hissing sound?“ you must first isolate when and how the hissing occurs.

Toilet Hissing After Flush

If the hissing occurs directly after a flush, it usually means that excess water or air is moving through the water line and into the tank. This could be an issue with several things, including:

  • Flapper. This rubber seal can deteriorate over time or wear down due to sediment buildup. This damage loosens the seal and causes water to leak.
  • Flapper chain. This is often an issue of an incorrect chain size. A chain that’s too long can slip out of place and cause leaks, whereas a chain that’s too short will cause a loose flapper seal.
  • Float. A malfunctioning float will cause the water to continue filling in the tank. This excess water will lift the flapper chain and loosen the flapper seal.
  • Fill valve. A worn fill valve means the seal is not entirely secure, and water can leak through.
  • Water pressure. If your water pressure is too high, the water quickly passing through the narrow supply line to your toilet can cause vibrations or what may sound like a hissing noise.

While some of these issues may require a simple fix, correctly identifying the problem will require some expertise. Simple repair or replacement parts are likely needed, but it’s also possible that more significant plumbing issues are to blame.

Toilet Hissing and Filling Slowly

This is often an issue with the refill valve. Either it’s clogged with debris, or it needs to be recalibrated or replaced. You’re likely hearing a hissing noise associated with a slow fill because the refill valve only allows a little water into the tank instead of shutting off as it should. This small opening creates a pocket of air pressure resulting in a hissing sound.

Toilet Hissing But Not Leaking

A toilet that’s hissing but not leaking usually indicates a loose internal part or sediment buildup. Often this is either the flapper or fill valve that has shifted out of place or worn down.

Toilet Hissing Randomly

Hearing a faint hiss from your toilet randomly throughout the day indicates that your fill valve is beginning to wear, and ignoring it could result in further damage or a leak.

Toilet Hissing Constantly

If your toilet won’t stop hissing, there’s likely a worn-out flap or broken fill valve. Call an emergency plumber to have either replaced and make sure there are no other issues with your toilet or plumbing system.

Related Content: A Simple Test for a Leaky Toilet Tank

Is a Hissing Toilet Dangerous?

It can be. A hissing sound in the toilet could indicate a damaged toilet part or a dangerous plumbing leak in your walls. Either way, it’s important that you call a plumber for emergency services. Leaving this issue unresolved could lead to further damage to your toilet or dangerous sewage leaks and water damage.

Related Content: 5 Signs You Need A New Toilet

How to Fix a Hissing Toilet — DIY or Plumber?

Most plumbing issues require a plumbing expert, including a hissing toilet. However, if you don’t find any major leaks or damage, there are a few simple adjustments you can try first to fix your hissing toilet:

  • Sediment buildup removal. If you notice sediment or debris buildup around the flapper or fill valve, clean or replace whichever is causing the issue and see if that resolves the problem.
  • Float or fill valve adjustment. Check whether the float or fill valve is correctly set below the fill line. If not, turn the screw clockwise or counterclockwise to raise or lower it. If you have an older style float valve, you may need to manually adjust it by pinching the float clip and adjusting it up or down.

If your toilet continues hissing despite these efforts, call your local plumber. A part likely needs replacement, or a more significant plumbing issue requires professional attention.

Listen to Your Hissing Toilet and Get It Repaired

No matter how loud or frequent, a hissing toilet is a sign of needed repairs. Don’t delay and risk further damage to your bathroom or plumbing. Count on your local experts at Benjamin Franklin Plumbing for emergency toilet repair. We don’t charge after-hours fees, even during holidays and weekends. Call us at 1-877-BEN-1776 or book an appointment online.