Two ways to create a watertight threaded seal

June 19, 2017

A leaking pipe can lead to mould damage, costly repairs and can really put a damper on your water bills. While a major leak is best left to a professional plumber, repairing minor leaks is well within the average DIYer’s capabilities. Learn how to prevent a leak from springing in the first place by creating a watertight threaded seal. Both pipe dope and plumber’s tape provide similar benefits, creating a seamless, leak-proof finish. [Photo Credit:]

Two ways to create a watertight threaded seal

Time: 5-15 minutes
Frequency: As required, usually one-time only
Difficulty: Easy
Tools: Pipe wrench, Teflon tape, joint compound, soft-wire brush.

Solution 1: Joint compound

Joint compound (or pipe dope) is both a lubricant and a sealant that can help two pipes connect and stay connected. It’s easy to apply in just a few steps. Pipe dope works on metal, but some brands might also work on plastic, so be sure to check before applying.

  • Clean up the threads to make sure there is no debris that will hinder the connection. Metal filings, dirt or oil need to be thoroughly removed before the compound is applied. You can use a cleaning solvent or just a clean cloth.
  • On the dry pipe ends, apply the compound with a brush that has not been contaminated with anything else. This “dope brush” ensures that the seal stays.
  • Apply the compound in a circular motion; be sure to coat both ends evenly for consistent torque and to prevent thread stripping.
  • Connect the two pipes and wipe off any excess joint compound.

Good to know!

Wire solder is another way to connect pipes, but you’ll need to heat it for it to work. Always be careful with this method and only use it on metal piping and areas that can handle the excess heat.

Solution 2: Plumber’s tape

Plumber’s tape, also known as Teflon tape, can be used on both metal and plastic threaded pipe fittings. It’s less messy than joint compound and takes only a few steps to apply.

  • Clean the pipe threads of both ends with a cloth to make sure there’s no debris that will prevent the tape from sticking.
  • Go with the direction of the threads when wrapping the plumber’s tape and keep the tension consistent to avoid thinner spots of tape.
  • Wrap from the bottom up, starting at about the second thread and ending at the top.
  • The loose end of the tape should be rubbed down with a thumb into the rest of the wrapped threads to form a cohesive seal. 

Good to know!

Plumber’s tape is not ideal for connections that already have their own form of a watertight seal, such as rubber seal, and should never be used on gas lines.

Preventing leaking pipes is easier when you start with a watertight threaded seal in the first place. Taking the time to ensure your pipes are connected properly and backed up with a joint compound or Teflon tape can provide you the extra peace of mind you need when it comes to your home plumbing projects.

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