Home Repair: How to Fix a Leaky Toilet

Toilets will sometimes leak. Unfortunately, this simple looking appliance in your bathroom is much more complex than you might imagine. Each type of leak that it can develop requires a different set of instructions for how to get it repaired. None of these repairs are hard to understand, but you must diagnose the problem and then follow the instructions that will guide to a successful repair.

Determine where the toilet is leaking.

If water is clearly seeping from around the base of the stool, the leak is most likely at the point where your stool connects to the sewer stack under the toilet. Finding water dripping from the back of the stool but not really on the flush box indicates that the gasket between the flush box and the stool is failing.

Or, it can mean that the gaskets under the bolts that hold the flush box to the stool have failed. Either way, this repair is about the same. If water is dripping from the flush box near where the water inlet is to the appliance, it is a problem with either the connection to the toilet or the riser tube.

Turn off the water to the toilet.

If you are lucky, the toilet was installed with a cut off valve near the floor at the rear of the commode. If you are not lucky, you will have to cut off the water to the whole house. Either way, avoid making a mess by turning off the water before starting to work on the appliance. Carefully remove the lid to the flush box and set it in a safe place until the end of the job.

Flush the toilet.

You need to get rid of as much water from the toilet as possible. There is water in the flush box and water in the stool. The easiest way to get rid of the bulk of this liquid is to flush the toilet. Hold the handle down until all of the water possible has drained from the flush box. If you are going to have to pull the stool, you will want to bail as much water as you can from the stool. Do the same for the flush box if the leak is associated with it.

Instructions: The leak is between the stool and flush box.

To fix this leak, you will have to separate the flush box and the stool.

Start by disconnecting the water inlet from the flush box. This is a fitting on the far right or left side of the bottom of the flush box. Usually, a pair of pliers is enough to grip the fitting and loosen it. If it is metal and tight, you may need a small pipe wrench or open end wrench that fits the nut. Put the wrench on the nut and reach inside the box and hold the flushing mechanism from turning. Gently apply pressure to the nut until it is loose.

Look for the heads of two bolts near the center of the inside bottom of the flush box.

Most of the time, these bolts can be removed with a slotted or flat screwdriver. You may need to put a pair of pliers or end wrench on the nuts on the other end of these bolts to get them loose. Remove the bolts. Grip the top edge of the flush box firmly and lift. You may need to rock it gently from side to side. It should lift up and away from the stool.

At this point, it is best to replace everything that connects the flush box to the stool.

Lay the flush box on its back on a flat solid surface. A table top or the floor will work. On the outside bottom of the flush box you will see a large gasket with a large plastic nut beneath it. Older commodes could have metal instead of plastic. You will almost always be replacing these with plastic, and it works fine. Pull the gasket off and unscrew the nut. This will let the tube sticking up in the middle of the inside of the box be able to be pulled out.

Clean the newly exposed areas with soap and water.

The flat portion of the back of the stool needs to be clean along with the inside and outside of the bottom of the reservoir. Having these areas clean will give you a better seal when the new pieces are installed. You can replace the entire tube assembly in the center of the box. Usually this can be purchased as part of a kit with the tube, gasket, new bolts and gaskets, and nut. It is really better to just replace everything rather than try to guess which piece is leaking.

Place the large thin gasket over the large end of the tube with the threads.

Push this through the large opening in the reservoir. Tighten the nut up to secure the assembly to the box. Slide the large thick gasket up and over the nut. The gasket is molded to fit over the hex shape of the nut.

Lift the box and push it firmly back into the opening at the back of the stool.

It should fit tightly enough to hold the box in place. Slip the gaskets over the bolts and up to the heads. Line up the holes in the box with the holes in the stool. Drop the bolts through the holes. Some assemblies have spacers that have to go between the box and the stool. Most replacement nuts have wings to help with the tightening. Tighten these nuts until the box is stable. Take care not to over tighten these nuts. You can easily break the ceramic of the stool or the flush box. You can tighten them more later if you have any minor leaks.

Reattach the water line to the flush box.

Turn on the water and let the box fill. After it has finished filling, let it set for about five minutes. Look for leaks. If it is going to leak, it will usually be the bolts that hold the box and stool together. If one is leaking, tighten it about a half turn or so. Continue to do this until the leak is stopped. Flush the toilet to make sure that it works properly to finish this repair.

Instructions: The leak is on the water inlet to the flush box.

Examine the connection where the water line attaches to the flush box.

If the leak is in the connection, tighten the fitting a little to see if the leak stops. If the leak stops, you are finished. Otherwise, try a time or two more to stop the leak by tightening the fitting a little more. This will usually do the trick unless the fitting is faulty. If the connection continues to leak or the leak seems to be coming from just above the connection, you will need to do more work.

Disconnect the fitting from the flush box.

At the point where the water connector enters the flush box will be a nut. Remove this nut to release the flush valve inside the reservoir. Have a bucket or trash can handy to catch any surplus water that may still be in the flush box. You will only need to change the gasket inside the flush box to fix this problem. Pull off the old gasket and put on a new one. Push the end of the assembly back through the bottom of the flush box and reattach it with the nut. Connect the water and turn it on. If there is a drip or oozing water, tighten the nut a little more to fix it.

Instructions: The leak is under the stool.

This is the leak that most people dread.

Disconnect the water line coming into the flush box. On each side of the stool near the floor is a small round cap. Use a flat screwdriver and pry these away from the base of the commode. Using a wrench or pliers, unscrew the nut from the bolt that is under the cap. This will release the commode from the floor.

Place some type of mat on the floor in front of the commode.

If you are strong enough, lift the entire toilet up and away from the bolts on set it gently onto the mat. Otherwise, recruit some help to get this done. Carefully lean the commode back until it rests with the flush box on the floor. Use a scraper and remove the old wax ring that may still be attached to the opening underneath the stool. You should wear some type of rubber protective glove for this process. Clean the remaining wax from the ring of the sewer pipe on the floor.

Remove the plastic cover from the new wax ring.

It may have a plastic flange. This should stay in place. Push the wax ring with the flange pointing downward onto the bottom of the commode. The ring should go around the opening in the bottom of the stool.

Lift the entire toilet and center it over the sewer opening.

Try not to let the new wax ring touch the floor. It will not hurt the floor, but it could damage the seal on the ring. Lower the commode until the opening from the toilet rests on top of the sewer opening. Watch as you lower into place that the bolts on each side of the sewer opening emerge through the bolt openings on the bottom of the commode. They may have wax on them from piercing the wax ring. This is normal. Just wipe away the wax.

Put the metal plastic rings back on the bolts and attach the nuts to the bolts.

Tighten the nuts until the commode feels solid to the floor. Do not over tighten these nuts because the commode can be easily cracked. Replace the plastic covers to complete this repair.