Why Is My Toilet Leaking From Tank Bolts When Flushed? Causes And Fixes

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You walk into your bathroom, take care of your business, and flush – only to find water spilling out from under the toilet tank. What’s going on here? Why is my toilet leaking from the tank bolts when I flush? Don’t worry. You’re not alone.

This is a common problem that many people experience. This can be caused by a variety of factors, including regular use and wear and tear or even a strong jolt or earthquake.

In this blog post, we’re going to show you why it’s happening and, more importantly, how to fix it!

What Are Tank Bolts?

Toliet Bolts,Tank to Bowl Stainless Stell 5/16inch by 3Inch Heavy Duty Bolts with Rubber and Stainless Steal Washers and Wing Nuts,Toliet Bolt

Tank bolts are essentially used to couple the toilet bowl to the tank. The tank part of the bolt will typically have rubber washers to prevent any leaks; however, over time, the bolts can simply get loose and need tightening or rust and need replacing.

If you have particularly hard water, then you may experience corrosion and mineral build-up on the bolts causing issues like leaks or a wobbly toilet.

Main Reasons Why The Toilet Leaks From Tank Bolts When Flushed

Photo by H2ouse

An unattended leaky toilet will lead to further damage in your bathroom that can extend to other parts of your home, so fixing the issue should be a priority.

  1. Bolts improperly installed that are either misaligned or simply the wrong size can allow water to leak.
  2. Bolts in older toilets can develop corrosion or rust and crack over time, in which case they will need to be replaced.
  3. If a bolt is either too tight or not tight, enough will create problems in the long run.
  4. The washers on the bolt have worn away or are cracked, which will cause a leak.

How to Fix a Toilet Leaking From the Tank Bolts

Photo by theplumbette

Fixing a leaking toilet tank bolt is an incredibly straightforward task for anyone armed with the proper information. Plumbers are expensive, so if you are someone who doesn’t have much experience, then the information below will be very helpful.

1. Where is the Leak Coming From?

Finding where the water is leaking from should be the first port of call. If the toilet is moving, then check the bolts as they may be loose, in which case an adjustable wrench will do the job.

On the other hand, the bolts could be corroded, or the washers may have deteriorated. In most cases, these parts are available in kits that include all the parts and are cheap.

Top Tip: If after checking you are still not sure where the leak originates then dry the area with a towel and pour some food dye in your toilet tank and check where the colored water emerges.

2. Empty the Toilet Tank of Water

The bolts are in the toilet tank, so to be able to work, and you will need to empty the tank of all the water.

  • Turn the water off by the stop valve situated behind the toilet at the base.
  • Empty the tank by flushing the toilet.
  • Mop up any water left using a sponge or an old towel.
  • Remove the water supply line.

4. Remove the Toilet Tank

Take this opportunity to inspect the tank for any cracks and all the bolts, nuts, and washers. If they are difficult to undo, then they may be made of metal and have rusted in place.

Use a small hacksaw to cut the bolts off if need be otherwise, unscrew the bolts and washers and remove the tank placing it to one side.

5. Replace the Tank Gasket

To ensure your toilet tank doesn’t leak after you reinstall it, replace the gasket that sits under the tank. This gasket is usually made of rubber, so push it into position and check that it fits properly.

6. Install the New Bolts and Washers

For ease, put all the bolts, washers, and nuts on the tank while it is lying on the floor. To create a perfect seal, ensure that the rubber washers are sitting against the tank. This will also help in absorbing any extra force due to over-tightening of the bolts.

  • Spray the bolts with an anti-rust spray to prolong the life of the bolt.
  • Thread a metal washer first and then a rubber washer on the long bolt and put it through the provided holes within the toilet tank.
  • The bolts should stick out from the underside of the tank. This time thread the rubber washers first and then the metal washers and place the nut over them, and tighten it.
  • Ensure not to tighten the bolts excessively, as this can cause the tank to crack.

7. Place the Toilet Tank in Place

  • Once the bolts are secured, thread the bolts that are sticking out the bottom of the tank through the mounting holes.
  • Ensure that the tank is sitting properly and the gasket is flush with the tank and in place.
  • Place a rubber washer followed by a metal washer and then the nut and tighten both sides by hand first.
  • Once you are confident they are straight, use a wrench to tighten the bolts completely.
  • Alternate the tightening process from one bolt to the other to ensure the tank is level

8. Turn Water Supply On and Inspect

  • Attach the water supply line back into the toilet tank.
  • Turn the water back on from the stop valve.
  • Inspect the surrounding area for any leaks.
  • Flush the toilet and check for any water leaking.

Why Is My Toilet Tank Still Leaking After Replacing The Bolts?

There are a few reasons why your toilet may be leaking after replacing the bolts.

  • If the bolts are loose, then they will need to be tightened.
  • Over-tight bolts can warp the gasket and start a leak, so the gasket may need replacing.
  • If the bolts are too tight, they can crack the toilet bowl which can be expensive to replace, so be careful.
  • If you are certain the bolts are not the cause of the leak, then check the flapper or wax seal at the base of the toilet.

FAQS Frequently Asked Questions

Are toilet tank bolts universal?

Yes, toilet tank bolts are the same length and width and can be used across different brands. They are 5/16 of an inch in diameter and the length can vary from 2 and 1/4 to 4 inches depending on your specific requirements.

Can I use a sealant to stop the leak?

Silicone sealant can be used for a temporary fix however the bolts will need to be replaced. Using a sealant will make the process of removing the bolts more difficult, due to the silicone residue that will be extremely difficult to remove, so we would recommend not using a sealant.

How can I stop my toilet tank bolts from rusting?

Bathrooms are the perfect environment for rust to develop so keeping metal bolts rust-free can be a challenge.

However, toilet tank bolts are available in brass which will not rust, you can also get metal bolts and spray them with a rust prevention spray to protect them and extend their life.

Will tightening the toilet bolts stop a leak?

Generally, tightening the bolts will most likely stop the leak, but if the toilet is old, the washers may have hardened and can crack, creating a bigger leak.

If the toilet is more than 5 years old we highly recommend replacing the bolts, washers, and tank gasket.

Do I need to hire a professional plumber to change the tank bolts, washers, and gasket?

Changing the toilet tank bolts can seem like a complicated process however if you follow the simple steps above, it will break the process down, and you can save money by doing it yourself.

How much will a plumber charge to replace toilet tank bolts?

Changing the toilet tank bolts is a time-consuming job because it involves taking the toilet tank off its seated position and replacing the bolts, washers, and tank gasket.

Depending on how hard your bolts are to remove a plumber can charge anything from $100 – $175.

How Do You Keep Your Toilet Tank Bolts From Rusting?

If you have stainless steel bolts, then spray rust protection on them before installing them, or better yet, get brass bolts and washers to avoid any chance of rust.

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