How to Use Teflon Tape to Repair a Leaky Toilet Connection

Teflon tape wrapped around a fitting


There’s a leak in the line connecting the toilet to your home’s water supply.

A visual inspection tells you the problem stems from the threaded connection between the water line and the bottom of the toilet tank.

Or the problem may lie with the threaded connection at the other end, between the supply line and the shut-off valve at the wall.

Those threaded connections! What’s a resourceful DIYer do? Run to the hardware store and waste an afternoon replacing leaky connectors?

Not when there’s Teflon tape lying about, an indispensable tool for any homeowner with more than a modicum of DIY repair ability.

It can certainly stop the leak, but you have to know how to apply it.

This blog will list the steps.

What is Teflon Tape?

Teflon tape, or “plumber’s tape,” is a thin, flexible white strip of polytetrafluoroethylene (PTFE). It works like a thread sealer, with a friction-resistant surface that creates an airtight connection between two threaded pipes.

For legal reasons, only the DuPont Corporation can use the Teflon name. However, most people refer to all PTFE tape as “Teflon,” regardless of its origin, the way all hot tubs have become “Jacuzzis.”

Teflon is not just for cooking, medical appliances, and waterproof fabric! No self-respecting plumber would be without it.

Several properties of Teflon tape make it ideal for waterproof seals in threaded pipe connections.

  • Great flexibility;
  • Great strength and resistance to tearing;
  • The thinness to fit into tight spaces.

Teflon tape acts like putty without the putty mess and inconvenience. Under the squeezing forces of a male and female connection (yes, we’re still talking about plumbing), it spreads out and fills the gaps between the threads. This action prevents water — and air, for that matter — from passing through the connection and causing a leak.

How to Apply Teflon Tape for a Watertight Seal


Teflon tape won’t do the job if misapplied. So here’s a step-by-step guide to fixing your leaky toilet supply line:

  1. Dry the threads of each connection, and clean the threads on the male connector of any debris.
  2. Wrap the male connector with Teflon tape. Loop twice at the lower end of the threads and work your way up, but don’t go past the end of the connector. It’s almost like regripping a tennis racket!
  3. Tape inside the joint can cause clogging and other problems. Overlap each loop by about half of the tape’s width.
  4. Follow the direction of the threads while wrapping. Keep the tape under tension as you wrap. Loosely wrapped tape will shift when you screw the connections together.
  5. After the last circuit, cut the tape and press the loose end into the threads of the connector. Nothing should protrude from the surface of the threads.
  6. Insert the male connector into the female connection. Screw it in by hand and finish the job with a wrench. No jokes, please.

Plumbing professionals often use Teflon pipe compound to make the joints extra-secure. If you go this route:

  1. Use your finger to apply a thin, even compound coating over the surface of a male connector already covered with tape. The compound usually comes in a squeezable tube.
  2. Screw the connection together and tighten it with a wrench.

Now, suppose you did all the work and followed our guidelines exactly, but the toilet’s still leaking.

Other problems can trigger leaks in your toilet’s supply line, including loose nuts at either end of the line.

So you’ll need to address each problem as it arises, or you may throw in the towel and call a professional plumbing service. DIY repairs will get you only so far; a leaky toilet can cause massive damage if not fixed promptly.


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