How To Fix A Toilet Leaking From Tank Bolts

A toilet leaking from the tank bolts is a very common problem. Most toilets are two pieces, a water tank and a bowl. When a toilet is flushed, gravity sucks the water stored inside the tank downward which flushes the bowl. Then the tank and bowl fill with water and wait for the next flush. The water tank is attached tightly to the bowl with 2 bolts that are located inside the tank. The bolts are made of zinc, which is resistant to rust, and contain two rubber washers. When the bolts are tightened, the washers compress and seal the hole. Over time, the bolts can start to corrode and the washers can deteriorate. This can eventually cause a leak.

A toilet that leaks from its tank bolts usually has damaged, misaligned or cracked washers and/or bolts. To fix the leak, you have to either tighten the bolts, realign or replace them. A set of toilet bolts only cost around $6-$10. You can buy them online or at any Home Depot, Lowes or hardware store that carries plumbing supplies. A plumber could easily charge over $250 to do the job so it’s worth doing this simple repair DIY.

To fix leaking toilet bolts, turn off the water to your toilet, flush the tank to empty it, and then remove the bolts. The only tool you’ll typically need is an adjustable wrench.

Once the tank is detached from the toilet bowl, remove and replace the bolts and washers with a new set and tighten them carefully. As long as your tank isn’t cracked, this will fix the leak.

Why Does A Toilet Leak Between The Tank & Bowl?

The most common cause of a leaky toilet tank are the bolts. A two piece toilet has a tank and a bowl which are held together by two bolts. The bolts have a rubber washer which seals the hole they pass through when the nut is tightened. If the nut is loose, or the washer has gone bad or is misaligned, the toilet bolt can leak.

Sometimes a leaking toilet bolt can be fixed by realigning or tightening it. However the best way to fix leaking toilet bolts is by replacing them. A bolt set which includes a new toilet gasket only costs around $6-$10 so it’s a very inexpensive repair that you can do yourself in about 10-15 minutes.

Rubber breaks down over time, so the rubber washer that seals a tank bolt can eventually cause leaks. A sure sign that you’re washers are bad, loose or misaligned is when the tank starts to wobble.

Here are the most common reasons why a toilet leaks from the bolts:

Toilet tank bolts and loose.
Toilet bolt washers are old and don’t provide a watertight seal.
The toilet tank is cracked.
Bolts are misaligned which creates a big enough space for water to pass.

Another reason your toilet tank is leaking could be the rubber gasket that connects the toilet tank to the bowl. If the gasket is old or damaged, the seal may not be water-tight which causes a leak.

Finally, if the toilet bolts are over-tightened it could cause a crack in the porcelain around the bolt. In this case you need to replace the entire tank. Simply replacing the bolts and washers won’t plug the leak.

Fixing Leaking Toilet Tank Bolts

Two piece toilets have a tank and a bowl which are attached by a set of bolts. The bolts pass through a hole at the bottom of the tank which line up with holes located in the bowl.

Most toilet tank bolts include rubber washers that sit between the bolt head and the inside of the tank.
Washers or spacers also sit between the tank and the bowl
Another washer made out of a metal, rubber or plastic sits on the bolt between the bowl and nut.

When tightened, the bolt, nut and washers secure the tank to the bowl and prevent it from moving and leaking.

A toilet that leaks from its tank bolts usually has damaged, misaligned or cracked washers and/or bolts. Before you replace the bolts, check their alignment.

If the someone accidentally bumped the tank when the bolts were a little loose, they may become misaligned. Drain the tank, realign the bolts and tighten. Fill the tank and see if the leak is still there.

In some cases the bolts may be aligned properly but a little loose. When the bolts become loose, the rubber washer decompress which doesn’t seal the hole as well. Water may be able to squeeze under the washer and down the hole. To fix the problem, simply drain the tank and tighten the bolts.

If you’ve alignment and tightened of the bolts but the leak is still there, go ahead and replace them.

How To Replace Toilet Tank Bolts

To stop a toilet leaking from the tank bolts, the bolts and washers will probably need to be replaced. Luckily a new set of tank bolts, nuts and washers only costs around $6-$10. It’s a fairly easy DIY project and the only tool you’ll need is an adjustable wrench.

Start by turning the water supply to the toilet off. Find the water supply valve and turn it completely off. Then flush your toilet to drain the tank and bowl.

If there’s a little water at the bottom of your tank that won’t drain, use a large cleaning sponge to soak it up.

Once your water is turned off and the tank is empty, follow the steps below:

Remove the tank bolts, washers and nuts from both the inside of the tank and below the bowl.
Lift the tank and check for damage.
Replace the old tank gasket if it’s faulty.
Gently place the tank back onto the bowl with the gasket in place.
Make sure the tank bolt holes are aligned.
Slip a bolt and rubber washer into each of the aligned holes. They’re located inside the tank at the very bottom.
Place a washer on the bolt under the bowl.
Tighten the nut. Start by hand tightening until it’s snug, then gently tighten it with a wrench. Don’t ever-tighten the nut or you could crack the porcelain.
Install the 2nd washer and nut.
Turn on the water and let the bowl fill.
Flush the toilet and check for leaks.

When you’re checking and/or changing the old tank gasket, be careful lifting the tank. Some toilet tanks can be heavy. If it’s too heavy for you to lift yourself ask a friend for help.

What To Do If The Toilet Tank Bolts Won’t Come Out

If your toilet tank bolts are damaged and/or corroded and the nuts won’t come off when you turn them with the wrench, you’ll have to cut them. This is easy to do with a hack saw.

Cut right through the nut and bolt with your hacksaw. Once cut, the toilet bolts will come right out.

I recommend using a hand-held mini-hacksaw to cut the bolts and not a reciprocating saw. A Sawzall is powerful and can damage the porcelain if it jumps off track and hits the toilet.

Toilet bolts are water resistant. But hard water can slowly corrode a set of tank bolts. This can be prevented by using solid brass bolts. But the standard bolts toilet come from are steel and/or zinc plated. If you have hard water, you need to change the stock bolts to brass by yourself.

If you don’t want to change the toilet bolts to brass, spray them with a rust protector instead. This can help protect them a bit.

If the bolts spin in circles instead of becoming loose when you turn the nut, you’ll have to use a lock wrench or screwdriver to help.

Use a screwdriver or the lock-wrench on the head of the bolt to keep it from spinning when you turn the wrench. Twist the nut until it starts to loose up.

If the nut is badly corroded to the bolt, you can use some WD-40 or Blaster PB Oil to help loosen it up.

How To Replace A Toilet Tank Bowl Gasket

When you replace a set of toilet tank bolts, it’s also a good idea to check the toilet tank bowl gasket. When the bolts are leaking there’s a good chance you’ve got an issue with the gasket too.

Most toilet bolt kits also come with a toilet tank bowl gasket because they’re generally changed at the same time.

The gasket is located at the bottom of the tank where is inserts into the bowl.

Once the toilet tank bolts are removed, lift off the tank and inspect the gasket.
Since a new gasket comes typically comes with the tank bolts, I’d change it just to be safe.
Remove the toilet tank bowl gasket by hand.
If it doesn’t come off, use a screw driver to wedge it off.
Put the new gasket on.
Removing and replacing a toilet tank bowl gasket is done by hand.
Once the gasket is on, place the tank back on the bowl.
Make sure the bolt holes are aligned.
Install the toilet tank bolts.

Once the toilet tank bolts are installed and tightened, the rubber tank gasket will seal.

Why Is My Tank Still Leaking After I Replaced The Bolts & Washers?

First, try tightening the nuts a little tighter. A toilet tank can leak after replacing the bolts and washers if they weren’t tightened enough to seal the rubber. However, leaks can also occur if you over-tighten the nuts. Make sure they’re snug enough to seal the rubber washer against the bowl but not too tight. Overly tight nuts can damage the rubber washers and gasket and possibly crack the toilet bowl or tank.

If the tank is still leaking after you’ve replaced the bolts and tightened the nuts, try a different style tank bolt. I like the type with a concave head that sits inside the curved hole. But they don;t work on every tank design. Make sure you buy a tank bolt that works with your bowl design.

The last thing you can try is some silicone. Apply 100% silicone to the hole, bolt and washer to seal the hole tighter. After the bolt is tightened, cover the head with silicone. Let is dry before filling the tank with water.

Last, you can try applying some rubberized waterproof tape on top of the bolt head. Tape helps prevent water from getting to the bolt where it can seep through the hole.

Do I Need To Replace The Bolts If Tightening Stopped The Leak?

If your leaking toilet tank bolts stopped leaking after you tightened them, you may still need to replace them. Check the condition of the bolts, washers and nuts. If they’re warn, old and/or corroded, then yes you should replace them. However, if they’re in good condition, then it’s not necessary. Toilet bolts can leak if the bolts aren’t screwed in tight enough so a leak doesn’t necessarily mean they’re bad.

How Do I Know What Toilet Tank Bolts To Buy?

Toilet tank bolts are universal, so any set can fastener any toilet. However, they do come in slightly different designs and materials. If you have hard water, buy a set made out of brass to keep them from corroding. Look inside your toilet tank. If the holes are flat, but a tank bolt with a flat rubber washer. If the hole is curved, buy a tank bolt that also has a curved head.

Toilet bolts come with either a wing nut or hex nut. I prefer the hex nut but either works fine. Buy the design you like working with best.

Should I Use Silicone To Stop A Toilet Tank Leak?

A sealant can temporarily fix a leaking tank bolt. But they’ll eventually degrade which causes the leak to come back. The best way to fix a leaking toilet tank bolt is to replace the bolts, washers, nuts and the tank to bowl gasket. However, you can use a little sealant, like silicone or rubberized waterproof tape, along with a bolt replacement for even more protection.

Will Tightening Toilet Bolts Stop A Leak?

Tightening loose toilet bolts will sometimes stop a leak. However, this only works if the cause of the leak was loose toilet bolts. If the leak is caused by a misaligned bolt or a faulty washer, simply tightening the bolts won’t work.

A bad rubber washer can be the cause of a leaky toilet tank. The best way to fix a leaking toilet with a bad washer is by replacing the bolts.
Misaligned toilet bolts can also cause a leaky toilet tank. Drain the tank, loosen the bolts, realign and tighten them to stop the leak.

Be careful when tightening toilet tank bolts to stop a leak. If the cause of the leak isn’t loose bolts, you could over-tighten them which may crack the porcelain.

How Do You Stop Toilet Tank Bolts From Rusting?

The best way to prevent toilet tank bolts from rusting is to use brass bolts. Unlike steel bolts, brass does not rust. Brass is also resistant to corrosion caused by hard water so it’s a good idea to use brass when it’s time to install new bolts. However, if you don’t want to spend the extra money for brass, there are a few things you can do which include:

Spray the bolt heads with an anti-rust spray.
Cover the bolts with silicone.
Cover the entire bolt head with rubberized waterproof tape.

Each of these fixes is temporary and will eventually need to be redone. But it’s cheaper in the short term compared to new brass bolts.

How Do I Know When Toilet Bolts Are Tight Enough?

Hand tighten the bolts as much as you can, then carefully tighten them until snug with a wrench. You’ll know they’re tight enough when the top tank is firmly secure to the bottom bowl without wobbling. When you fill the tank with water and flush, the bolts won’t leak. If the bowl leaks or wobbles, you need to tighten them a bit more. Do not over-tighten the bolts because it can crack the porcelain.

Toilet bolts do not need to be super tight. You only need to tighten them enough to firmly secure the tank to the bowl and seal the hole with the rubber washer.

Quick Fix For leaking Toilet Tank

If your toilet tank bolts are leaking and you need a quick fix, here’s what you can do. Turn off the water and drain the tank by flushing. Sop up any remaining water in the tank with a sponge. Apply 100% silicone around the head of the bolt and washer. Push silicone into all the cracks with your finger. Then cover the silicone and bolt with some rubberized waterproof tape. The tape and silicone will contain the leak until you have time to replace the bolts.

How Do You Fix A Toilet Leaking From The Tank Bolts?

In order to fix a toilet that’s leaking water from the tank bolts, you should replace the bolts, washers, and toilet tank gasket.

Here’s a step by step list of how to do it:

Turn off the water supply to the toilet.
Flush the toilet tank to empty it.
Use a sponge to dry up any water left in the tank.
Remove the toilet tank bolts.
Lift the toilet tank free of the bowl and inspect it for cracks. If it’s cracked, replace it with a new tank.
Remove the old tank gasket and replace it with a new one.
Put the toilet tank back into place on the bowl.
Make sure the bolts holes are aligned.
Install new tank bolts and washers. I recommend using brass bolts.
Carefully tighten the tank bolts. Do not over-tighten the bolts or you could crack the porcelain.
Turn the water on and flush the toilet while checking for leaks.

Following these steps is the best way to fix a toilet with leaky tank bolts.

It’s safer to remove and replace old leaking bolts than it is to try and tighten old bolts because there’s a risk of over-tightening which could damage the tank. A bolts set which includes new bolts, washers, nuts and a tank gasket only costs around $6-$10 so it’s a relatively cheap repair.

Summary: How To Fix A Toilet Leaking From Tank Bolts

A toilet that leaks from its tank bolts usually has damaged, misaligned or cracked washers or bolts. To fix the leak, you have to either tighten the bolts, realign or replace them. A set of toilet bolts only cost around $6-$10. You can buy them online or at any Home Depot, Lowes or hardware store that carries plumbing supplies. A plumber could easily charge over $250 to do the job so it’s worth doing this simple repair DIY.

To fix leaking toilet bolts, turn off the water to your toilet, flush the tank to empty it, and then remove the bolts. The only tool you’ll typically need is an adjustable wrench.

Once the tank is detached from the toilet bowl, remove and replace the bolts and washers with a new set and tighten them carefully. As long as your tank isn’t cracked, this will fix the leak.

If you have any questions about how to fix a leaking toilet, email any time.