Learn how to find and fix common toilet leaks.

Finding & Fixing Toilet Leaks

Water on your bathroom floor? Don't stress, help is here!

If you're concerned about some water that you found on your bathroom floor (near your toilet), please rest assured that there are a number of common possible causes for the problem. After you eliminate the most obvious cause (bad aim), consider the following before presuming the problem is with the seal between your toilet and the sewer line. Usually, the issue is less costly than the potentially expensive possibility of wastewater coming up from beneath your toilet.

The Two Best Places To Start

Condensation: Probably the most common cause for excess water on the floor of a bathroom is water condensing on the outside of the toilet's tank and dripping onto the floor. This is commonly referred to as the tank "sweating." Tank condensation/sweat is caused by the difference in temperature of the water inside the tank, which is usually very cold, and the temperature of the air outside the tank in the bathroom, which is often warm and steamy. Tank condensation sometimes occurs more often in the summer months rather than the cold winter months, but can occur any time of year if the conditions are right. There are easy solutions to this type of problem, such as toilet tank liners (which insulate the cold water inside the tank from the humid outside) or anti-sweat toilet tank valves (which mix cold and warm water coming into the tank to reduce the temperature variance inside and outside the toilet tank). Unfortunately, it's not convenient to confirm the water on your floor is completely an issue of tank condensation/sweat. Basically, you will need to wipe the outside of your tank thoroughly with a towel and then over time, try to visually detect whether or not water is gathering on the outside of the tank again.

Water leaking from inside the toilet tank: Once you've confirmed that the problem you're experiencing is not due to tank condensation, then the next best place to begin would be to eliminate the possibility of you having water leaking from the tank itself. This is a fairly easy thing to check. Start by removing your toilet tank lid (be very careful, because tank lids are extremely fragile, can be heavy and are usually slippery when wet) and add some organic-based coloring (such as food coloring) to your toilet tank water. We even offer color test tablets on our site for this specific purpose! They can be obtained free with any order placed through our web site.

After adding the coloring, do NOT flush the tank, but instead wait a little while for the tank water to change color and settle. If after about 10-15 minutes (without flushing the tank) you find the water on your floor to be the same color as the colored water inside your tank, or if you see any colored drips coming from anywhere on your tank, then you'll know you have water escaping from the toilet's tank since that IS the only place you have the colored water.

The next thing to do would be to identify where the water is coming from. Any cracks in the porcelain tank should be discolored and highlighted by the tinted water. The tinted water will usually help in finding any leaks around the bolts and rubber seals between your tank and bowl or from the foam gasket where the flush valve allows water to enter the bowl.

  • Leaking from between the tank and the bowl: This is something you can detect with the colored water test that was described above. If the water appears to be leaking from between the tank and bowl, near the center, you may need a new tank-to-bowl sponge gasket, or new washers for the tank-to-bowl bolts. If water is leaking from the tank to bowl gasket it will tend to leak more often when the toilet is flushed. If the water is leaking past the bolts and washers, the leak can often appear to be closer to the sides of the toilet bowl, nearer the edge and farther from the center, but not always.

    These types of leaks can be difficult to pinpoint since the water can leak out of the tank and onto the bowl portion hidden by the tank. All bowls are unintentionally made slightly different due to how porcelain is manufactured. One bowl may have a low side towards the front of the bowl inlet hole, and another bowl may have a low side towards the back of the bowl inlet hole, or another one may have the low side on one of the sides of the bowl inlet hole. Water will naturally flow to the lowest point.

    To confirm and repair such a leak, it will be necessary for you to remove the toilet tank from the toilet bowl and replace the washers and/or sponge gasket as necessary. This process and the parts required can vary, depending upon your toilet model. We do offer "fit most" tank-to-bowl sponge gaskets and bolt sets on our site. If you're changing the tank-to-bowl rubber washers, it would be a good idea to take the opportunity to replace the just as old tank-to-bowl bolts as well.

  • Fill valve shank gasket leak: Do not forget to check the shank gasket where the fill valve attaches to the tank. The fill valve (also known as a "ballcock") is the valve that allows water to enter into the tank. The shank gasket is attached to the fill valve on the inside of the tank. This type of leak can also usually be detected by the colored water test. Check for possible cracks in the porcelain around or near the gasket. If no cracks are detectable in the porcelain, you may be able to just tighten the shank nut underneath the tank to stop the leak. We suggest you tighten the nut a 1/4 turn at a time while checking to see if the leak stops. If the leak still persists, then you will need to replace the gasket.

  • Leak from the fill valve refill tube: If the leak appears to be coming from the back, near the top of the tank, then check to make sure the refill tube has not come loose from the overflow tube on the flush valve.

  • Cracks in the tank: Unfortunately, there's no reliable way to repair a crack in a porcelain fixture. It will be necessary for you to replace your toilet tank or install a new toilet.

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Other Possibilities

shutoff valve

Leaking shut-off valve: Make sure water isn't seeping from the pipe connection behind the shut-off valve, near the wall. If it is, the valve may need to be replaced (although it may be possible for you to tighten the valve onto the pipe, depending upon the type of valve and pipe you have).

Leaking supply line: Check for water dripping from the nuts on each end of the supply line, where the line attaches both to the inlet of the toilet's fill valve (on one end of the flex) and the shut-off valve on the wall (at the other end of the flex). If you have a rigid supply line, you can try replacing the supply washers. Sometimes the supply line will be attached directly to your shut-off valve as a single piece unit. We recommend using flexible stainless steel water flexes as they are easier to attach and are very reliable. If you do have the single piece valve-with-supply-line, we recommend replacing it with a separate shut-off valve and a flexible supply line (two separate pieces).

Water coming from elsewhere in the bathroom: Very often, your toilet will be the lowest fixture in the bathroom causing water from the shower or the bathtub to pool at your toilet. This will make it appear as if the water is coming from the toilet when in fact the cause is much simpler and less expensive. You can try adding a throw rug, or two, to your floors to see if this eliminates the problem.

And Finally

Wax toilet gasket

Leaking from underneath the toilet: The wastewater should only seep past a bad wax ring if the water is backing up from further down the line. Even when a wax seal is bad, the water that is being flushed through a free drain shouldn't escape past the wax on the closet flange (beneath the toilet) and onto the floor as the water is dropping straight down, directly from the toilet and into the waste line. If the water on your floor is obviously wastewater (indicated by its coloring and noticeable smell), then your problem is likely more than just a bad wax ring. Although you may not be experiencing a recurring overflow problem with your toilet, the water is still most likely backing up and out through the first point of least resistance (from beneath your toilet). Along with resealing your toilet bowl (with a new wax ring and perhaps caulking around the base), we strongly recommend you investigate the possibility of a stoppage in your waste lines. In that case, simply replacing the wax ring would not solve your issue and you could then encounter increased drainage problems due to the existing stoppage in your lines. The new wax ring may then fail if the wastewater was continually backing up to it.

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Please note: The information provided above is GENERAL information only and is intended to address the most common problems with toilets that do not use manufacturer-specific parts. If you are uncertain of the type of parts your toilet requires, we strongly recommend you contact the manufacturer of your toilet or perhaps consult with a local plumber for their professional advice.

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