How to Fix a Toilet Leak

One of the most common plumbing problems that will occur over time in most homes is a toilet leak that can go undetected until a bill brings it to your attention. Most if not all common toilet leaks can be addressed by the homeowner without calling a plumber saving you money with a little knowledge.  How do you fix a toilet leak?

Run a Dye test to locate the leak:

  1. Toilet Flapper Leak-Dye shows in bowl
    Shut off H2O to tank
    Flush to empty
    Replace Flapper
  2. Fill Valve Leak
    Lower clamp/adjustment screw on float
    Adjust float to approx.1″ below overflow pipe
    If Valve is broken/leaks-Replace
  3. Toilet Base Leak-Dye shows up at the base
    Replace Wax Seal


For most toilet problems, as long as a homeowner is aware of sights and sounds that are out of the ordinary then a small problem won’t end up a bigger one and can be done easily without the plumber being involved. Conserving water along with saving money by doing it yourself could be worth the small amount of time and effort. Read this article to find out how.

How to Fix a Leaking Toilet


Toilet Flapper Leak

One simplest but most common problems is the Flapper that seals the water from the tank that flushes the bowl is stuck or worn out. If the Flapper is not aligned and sealing the toilet tank flush seat then the water will run into the bowl and out the drain. The tank will keep filling to compensate.

This is a huge cost after a period of time and a waste of water. You may hear water trickling through the toilet or a flush when not being used. It’s a simple fix just change the Flapper inside the tank (for as little as 5-10 bucks)

To Fix

  • Shut off the water supply to the toilet and flush the tank to empty it
  • Replace the Flapper
  • Make sure that it sits and seals off the toilet tank to from losing water to the bowl.
  • This should stop the toilet from leaking.


Fill Valve Leak

The Fill Valve float is the device that controls the intake of water moving into the tank through a hose that is inserted into the overfill tube. If the float is not set properly or worn out then water will continue to run through the overfill wasting water down the drain.

This will be a silent type of leak. Take the toilet tank cover off and inspect the setting.  If you don’t see at least an inch or so between the water level and the top of the overflow pipe then the water will run and continue to be wasted until it’s attended to.

To Fix-Just let some water out of the tank through the Flapper and lower or raise the clamp on the Fill Valve float. Some Assemblies have screw adjustments for easier settings. If Fill Valve is broken and won’t adjust or leaks from the seal at the bottom or at the top located under the cap, then it’s time to replace it. 

Fill Valve Replacement

  • Shut off the water supply
  • flush tank to empty
  • Disconnect the water supply line under the toilet tank
  • Keep a bucket or towel handy for the water that’s will drain out
  • Losen the nut on the Fill Valve at the bottom of the tank
  • Remove Fill Valve
  • Replace and install using the old valve as a comparison





How to Check for Toilet Leaks With Food Coloring


To find out if your toilet is leaking when the leak is silent and harder to detect or distinguish where it’s leaking from, try this old remedy. Dye in the toilet tank will indicate whether or not water is going somewhere it’s not supposed to. There is a dye detection found in the hardware store that you can buy in tablet form or you can just use food coloring.


  • Drop around 10 drops of food coloring or so in the toilet tank 
  • Wait 15-20 minutes
  • Look into the bowl 
  • If there is color in the bowl then the toilet is leaking (normally the Flapper)
  • If there is a color on the floor then the leak is at the toilet’s base (normally the Wax Seal)


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Toilet Leaking From Bottom of Tank


Toilet Base Leak

Maintenance Warehouse® Universal Toilet Wax Ring, Brass Bolts, Plastic Washers | HD SupplyA base leak is a water leak at the bottom of the toilet where it sits on the floor. This is the worst-case scenario as the water from the tank can ruin the floor, underlayment, or walls in your bathroom. If you see the colored dye that you added earlier to test for leaks coming from the base of the toilet then this is where the toilet is leaking water.

This can be fixed  90% of the time with a Wax Seal that seals the toilet to the drain.

I can tell you from good experience that you can do this job by yourself but installing the toilet onto the new ring and toilet flange can be a little tricky depending on the weight of your toilet so get a partner for a quicker easier experience.

To Fix-Check this video out for swapping out a Wax Seal!







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JimGalloway Author/Editor





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