How to Repair a Leaking Supply Tube to the Toilet

Updated February 21, 2017

If you come into your bathroom and find a pool of water at the rear of the toilet, you might have a problem with your supply tube. These tubes carry water from the water supply valve located behind the toilet to the toilet tank. A coupling at either end connects the tube to the water supply valve and the underside of the tank. These tubes can fail in a number of places. Repairing a leaking supply tube to a toilet isn't difficult, and should be done as soon as possible to prevent further water damage.

Examine the toilet supply tube and determine where it is leaking. This could be in one of three places: the coupling where the supply tube attaches to the water supply valve, the coupling where it connects to the tank, or the supply tube itself.

Turn off the water supply for the toilet where you want to repair the leaking supply tube. The water supply valve can be found on the wall behind the toilet. Rotate the valve on the end of the valve clockwise to turn off the water.

Unscrew the supply tube from the water supply valve. Examine the gasket inside the coupling and replace if needed. Apply pipe thread compound to the threads on the supply valve outlet. Tighten the coupling with the pliers.

Remove the toilet tank lid. Flush the toilet. Continue to hold down the handle until the water inside drains out. Wipe up the excess water with a sponge. Unscrew the coupling from the underside of the tank. Examine the gasket on the inside of the coupling and replace if needed. Wrap the threads on the tank inlet with plumber's tape. Reattach the coupling and tighten with the wrench.

Dry off the supply tube. Start wrapping repair tape about two inches above where the leak in the hose is. Continue wrapping for another two inches past the leak. Repeat the process in reverse from the other side of the leak.

Restore the water supply by rotating the knob on the end of the water supply valve counterclockwise.


Repairing a leaking supply tube with repair tape is a short term measure. The tube should be replaced as soon as possible.

Things You'll Need

  • Pliers
  • Sponge
  • Gaskets
  • Pipe thread compound
  • Plumber's tape
  • Repair tape
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About the Author

Nathan McGinty started writing in 1995. He has a Bachelor of Science in communications from the University of Texas at Austin and a Master of Arts in international journalism from City University, London. He has worked in the technology industry for more than 20 years, in positions ranging from tech support to marketing.