How to Fix A Toilet Leaking From Tank Bolts?

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A toilet leaking from tank bolts is usually a sign that the tank’s fasteners are cracked, misaligned, or have become damaged somehow. Or, in some cases, that the bolts have simply been screwed on too tightly. 

Remember that a leaky toilet leaking in any way, shape, or form is never good — especially when it comes to saving on your water bill. 

So, how do you fix a toilet tank bolt leak?

How to Fix a Toilet Leaking From the Tank Bolts

With most old and new models, the bolts on a toilet run through the tank and connect it to the bowl. You’ll find a rubber or — more likely — a metal washer sitting between the inside of the toilet tank and the bolt head. 

These washers can also sit between the bowl and the tank. Their purpose is to secure the two and prevent the latter from moving around. 

As they’re typically made of metal, hard water can cause them to corrode over time.

Step 1.  Perform an Inspection to Find the Leak Source

Before you can fix the leak, you’ll need to closely inspect the toilet tank bolts to see where it’s originating. 

Do the bolts appear loose? 

Are they corroded? If this is the case, you’ll definitely need to replace them with newer ones. 

And the same thing goes for the washers and nuts holding the bolts in place. These parts can wear out over time, causing a tank bolt to loosen — which can be dangerous for the tank. If your bathroom stays on the more humid side, this is something to keep an eye on as they may corrode at an accelerated rate.

Note that there are a few other places where your toilet can leak, too. To perform a thorough inspection, start at the bottom of the toilet, near the floor. 

Are there any puddles of water? 

Next, work your way up the back of the toilet — where the bowl connects to the tank. If you look at the space between the two, you should be able to determine where the leak is starting.

Step 2. Turn Off the Water and Empty the Toilet Tank

Now that you’ve zeroed in on the cause of the leak, cut off the water supply line before doing anything further. You can do this with the toilet’s water supply valve, which is located near the back wall of the toilet, typically on its left side. 

Take an adjustable wrench and loosen the nut on the valve. Then, turn the valve clockwise about a half-inch to shut it off completely.

If the toilet still runs, you’ll need to turn the valve a bit more. After turning off the water supply line, flush the toilet to empty all of the water from the bowl. Next, remove any remaining water from inside the tank.

Step 3. Remove the Toilet Bolts and the Tank

Once you’ve removed all of the water from the tank, grab a wrench and remove the nuts connecting the tank to the toilet bowl. 

Remember that these nuts shouldn’t be secured too tightly, though, in some cases, they may be too corroded to turn just by using your hand. 

If this is the case, take your pliers and firmly grab the nut or bolt head, and slowly turn it to the left. You may also need to tap it a few times with the end of the pliers to break up some of the rusted metal. 

If you still run into trouble, take a bit of CLR and spray it on the fastener. Let it sit for a few minutes and then try it again. 

Once you have the tank bolts removed, ensure that the toilet lid is down, and then carefully lift the tank out of its position. Next, place it on top of the toilet lid so that you can begin working on it. 

Step 4. Replace the Fasteners and Bowl Gasket as Needed

Be sure to set all of the old fasteners to the side so that you won’t mix them up with the new hardware. 

Depending on the make and model of your toilet, you may also need to remove the bowl gasket — a round piece of rubber that sits between the tank and the toilet bowl. 

These rubber gaskets are known to cause water leaks when they become worn or hard — though this is more common in toilets 7 to 10 years old. 

Next, take a look at the instructions that came with your new hardware or tank kit (such as this Fluidmaster kit), and set out the pieces to avoid losing them. Sometimes kits will include an extra set of nuts and metal washers (or even rubber washers) just as a safety measure. 

Once you’re familiar with where everything goes, place the bolts in position on the tank. If you’re replacing the gasket, place it on the bottom of the tank before moving on to the next step. 

Step 5. Place the Toilet Tank Back In Position

Next, carefully lift the tank off the toilet lid and place it back in its position. Once you have lined up the bolts with their respective holes, take your nuts and washers and secure them. 

Make sure not to over tighten them! This can cause cracks in the toilet bowl and the tank, and if this happens you’ll need to put a “Do Not Use” sign on the toilet until you get a replacement bowl or tank. 

Before moving on, remember to do a quick check to ensure that you’ve installed all the bolts and necessary nuts and washers on the tank.

Step 6. Turn the Water Valve Back On

Now it’s time to turn the water back on and check if the leak is gone. 

Take your adjustable wrench and turn the water valve counter-clockwise to hand tighten it. Next, get up close and personal with the toilet tank to monitor for any leaks. 

Be sure to check both sides, the back, and the area around the bottom of the bowl. Flush the toilet a few times just to be on the safe side and stand there and watch as it fills. 

You’ll also want to monitor the area around the main water connection to ensure that no leaks spring up there and that your fix worked. 

The Bottom Line

And now, my friend, you know how to repair a toilet that’s leaking due to bolt issues! Did all of the steps make sense? Do you think you’re ready to do it on your own? 

Overall, the process may take anywhere from 30 minutes to an hour. But if you get stuck at any point, or come across an unexpected issue, it’s always best to contact a licensed plumber to get a bit of guidance — today (and thanks to smartphones), many plumbers can even do a consultation over the phone for a small fee. 

Hope this helps!

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