Depending on whether you DIY or hire a professional plumber.
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What you'll need:
TOOLS
Kit of nuts, bolts, and washers
Rust protector (to prolong the life of your tank bolts)
Bowl gasket
Sponge
Gloves
Bucket
Towel
SUPPLIES
Adjustable wrench
Mini hacksaw
Screwdriver
Pliers
If you discover water leaking from your toilet tank bolts—you’ll want to address the leak immediately to stop any damage from occurring (and in the worst case, having to figure out how to make a water insurance claim).
Whether you’re handy with bathroom fixtures or if you need to find a plumber near you, we’ve come up with five steps to ensure your toilet leak gets fixed fast and efficiently.
5 Steps to Fix a Toilet Leaking From Tank Bolts
We recommend that only experienced homeowners with plumbing knowledge take the lead for this project. Those that are skillful can locate toilet tank bolts by lifting the lid of the toilet tank—you’ll see two tank bolts that run from the bottom of the toilet tank to connecting holes in the toilet bowl.
Toilets leaking at the base is typically a sign that the bolts or the washers—the part that secures the bolts from the tank to the bowl—are damaged, misaligned, or cracked.
Figure Out the Source of Your Toilet Leak
Photo: Elena Loginova / Adobe Stock
If you see water pooling on the floor next to the toilet, you’ll want to check all toilet areas to find the source of the leak.
Start at the bottom of the toilet and feel your way up. Check if the toilet tank is wobbling—if so, you may only need to tighten the tank bolts with an adjustable wrench to fix the leak.
If tightening the bolts does not stop the leak, you’ll need to check whether the bolts, washers, and nuts are rusted or damaged. You may need to replace these parts entirely. Universal tank bolt kits are easy to find and purchase—averaging $5 per kit.
If you’re unsure where your toilet leak is coming from, you can reach out to a plumbing repair expert in your area to save you time, money, and hassle.
Turn the Water Off and Empty the Toilet Tank
Locate the water supply valve—usually found behind the left side of the toilet.
Place a small bucket underneath the valve to catch excess water.
Grab your adjustable wrench, loosen the nut on the valve and slowly turn clockwise until you shut the valve off.
Flush the toilet to empty any water from the toilet bowl.
Take off the tank lid and place it in a safe spot where it won’t break.
Remove water remaining inside the toilet tank with a sponge. Wring out the water in your bucket.
Remove Tank Bolts, Fasteners, and the Toilet Tank
Photo: New Africa / Adobe Stock
Check the condition of the nuts, bolts, and washers. If they’re metal, they may be rusty and difficult to disconnect with a wrench—you may need to saw them off with a mini hacksaw.
Otherwise, grab a wrench, pliers, or a screwdriver. Loosen the nuts, then turn bolts to the left until they disconnect.
Remove all bolts, nuts, and washers from the tank and the bowl. Lift the tank up—lay a towel on the ground, and place it on its side. While everything is removed and visible, take a moment to check for mold or mildew that may be a result of the water leak.
Replace Old Toilet Fasteners
Take all loose parts and place them in a separate area from your new replacement kit parts.
When changing your nuts, bolts, and washers, you’ll also want to replace the bowl gasket—the round rubber piece that sits between the toilet bowl and the tank to prevent leaks in the future.
Place the new gasket on the bottom of the tank, open your kit and make sure you have the correct replacement parts.
Pro Tip: You may want to purchase additional washers—metal and rubber—to add an extra layer of security to your tank bolts.
Fasten Toilet Tank Bolts and Turn the Water Valve Back On
Photo: LIGHTFIELD STUDIOS / Adobe Stock
You may need another person or a professional plumber to hold the toilet tank in the correct position for this step.
Align tank bolts with connecting holes.
Place a metal washer followed by a rubber washer on the bolt.
Slide the tank bolt into the hole and add another washer to the bolt under the tank.
Put a nut on each bolt underneath the tank. Tighten the nuts with your hand—and then gently use a tool tightener.
Carefully lift the tank and place it over the holes on the bowl.
Add a third rubber washer—and an additional metal washer on the tank bolt, followed by a nut under the bowl. Gently tighten.
Double-check to ensure you didn’t miss installing the tank bolts, nuts, and washers inside and below the tank—and under the bowl.
Grab your water supply line. Hand turn the nut counter-clockwise, turn the water back on, and let the tank fill up.
Flush the toilet a few times—feel around the tank, bowl, water valve, and tank bolts for any leaks.
Pro Tip: If you secure the fasteners too tight, it can cause the porcelain to crack.
DIY Repairing a Toilet Leak From Tank Bolts vs. Hiring a Pro
Only DIYers with prior plumbing experience should tackle this project. We estimate you’ll save several hundred dollars repairing your own leaky toilet tank bolts.
If you’re unfamiliar with leaks and toilet parts, we suggest consulting a professional plumber in your area for toilet repair costs—with the average coming in at $240. While this may seem expensive for a seemingly simple fix, it’s a good way to make sure the job is done right and rule out any other issues at the same time.
For example, the signs of loose tank bolts and a toilet fill valve leaking are pretty similar and both often result in puddles of water on the floor by the base of the toilet. A plumber can help you diagnose the true problem and fix it all at one time without the time and cost of doing it yourself (and potentially doing it wrong).
Frequently Asked Questions
You definitely can over-tighten toilet tank bolts. Unlike some other materials, porcelain can’t bend or flex, so when you over-tighten a screw into it, it could break against the added pressure. Only tighten them as much as needed to keep them in place and firm; any more and you could risk breaking the porcelain.
If a bolt at the bottom of your toilet tank is loose, it can directly cause a leak. If a bolt securing the toilet base to the floor is loose, it won’t directly cause a leak but can lead to the same result over time. That’s because the loose bolts will eventually move the wax seal or cause cracks in the bowl from the toilet being wobbly.
Sealant doesn’t need to be applied to the bolts, but it can be a good way to stop an active leak in the moment. However, don’t rely on it as a cure-all; instead, make sure to fix the problem at the source by changing or tightening the bolts.
If you do use sealant, make sure to spread it thickly and evenly across the bolts and the tank's porcelain.
Silicone-based caulk is known for its waterproofing qualities, so it’s the best option for any bathroom area. While it’s often more expensive, it will provide a better, longer-lasting seal than acrylic or latex caulk. Use it along the base of the toilet to prevent leaks and keep the area clean and protected.
Xiao is a full-time writer giving advice and tips on improving living spaces so it functions as a peaceful sanctuary and an efficient factory. She is visual artist with substantial woodshop experience and isn’t afraid to pick up a circular saw. She is also a volunteer builder for Kansas City’s Habitat of Humanity.
Xiao is a full-time writer giving advice and tips on improving living spaces so it functions as a peaceful sanctuary and an efficient factory. She is visual artist with substantial woodshop experience and isn’t afraid to pick up a circular saw. She is also a volunteer builder for Kansas City’s Habitat of Humanity.
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