How to stop a leaky joint using thread sealant tape or pipe dope

Whether a new pipe is installed incorrectly or an old pipe develops a nagging leak over time, common household fixtures like sinks and toilets are prone to leaky pipe joints. If you discover a leak in your kitchen or bathroom, you’ll want to stop it before it causes more serious damage. With a little research and the right tools, sealing a leaky joint is a DIY job you can complete like a pro. [Image credit: iStock.com/Scukrov]

Time: 20 minutes
Frequency: As required
Difficulty: Easy
Tools: Clean rags, adjustable wrench, sealant tape and/or pipe dope.

If you discover a leak in your kitchen or bathroom, sink, stop it before it causes more serious damage. Read below to find out how sealing a leaky joint is a DIY job you can complete in no time at all.

Threaded pipes and fittings are prone to leaks if they aren’t securely sealed. To avoid leaks and long-term damage, threaded connections between metal or plastic pipes must be properly sealed.
For an airtight seal, use pipe thread sealant tape (also called plumber’s tape) and/or pipe dope to fill the gaps between male and female threads

Also commonly referred to as plumber’s tape or Teflon tape, this is a type of pipe sealant that comes on a roll similar to electrical tape or masking tape.

• Apply pipe tape by wrapping it around the threaded end of a pipe or fitting.
• Often used on connections that occasionally need to be disconnected or replaced. For example, bathroom sinks or toilet shutoff valves where leaks are more common.
• Plumber’s tape is colour-coded by type and comes in low and high density, varying in quality and price.

Good to know!
Plumber’s tape is less messy than pipe dope, but if it’s wrapped incorrectly (in a counter-clockwise direction), the tape can ball up as the fitting is tightened, ruining the seal.

Pipe dope is an adhesive-type mixture applied to the threaded end of pipes. It is also known as pipe joint compound or pipe glue.

• Pipe dope is usually applied with a brush. The process is messier than pipe tape but also faster.
• Generally speaking, pipe joint compound creates a more durable and airtight seal than pipe joint sealant tape.
• It’s often used for pipe and fitting connections that are considered permanent. For example, gas or water pipes that are buried underground or run beneath your home, and are less likely to be disconnected.

Good to know!
Both pipe dope and plumber’s tape are available in various types designed for a water line or a gas line use. Read the packaging carefully to make sure you select the right product for your application.

To apply plumbing tape for leaks:

• Clean the pipe threads with a rag before applying the sealant tape.
• With the end of the threaded pipe facing you, wrap the tape clockwise (in the direction of the threads). Do not let the tape lap over the end.
• Wrapping the tape three times around the threads is sufficient. Occasionally, you'll run into a loose fitting that requires four or five wraps.
• As you wrap, keep tension on the tape so it’s pulled into the threads.
• Stretch and tear the tape to finish.
• Connect the threads by hand, then tighten the connection with wrenches.
• If you loosen or disconnect a fitting, remove the old tape and re-wrap it with a fresh piece.

To apply pipe dope for leaks:

• Apply the compound to the threads with the supplied brush.
• Do not use too much of the compound; a little goes a long way.
• Start the threads by hand, then tighten the connection with wrenches.

Good to know!
When working with pipes, make sure the main water supply line is turned off.

To ensure a tight seal, some plumbers choose to use a thread sealant tape and pipe dope together. To do so:

• Apply the thread sealant tape.
• Spread a thin layer of pipe thread sealant (pipe dope) over the tape. (If you're working with plastic pipe, choose a compatible compound.)
• Start the threads by hand, then tighten the connection with wrenches.
• Wipe away the excess. The pipe joint compound will fill any gaps caused by tape failures.

Good to know!
Be careful when tightening a joint; over-tightening can result in an even worse leak.

Leaky pipe joints are easy to fix with a few tools and the right attitude. Rather than ignoring an annoying leak or facing long-term water damage, take on this common DIY project with confidence and you’ll have a secure, leak-proof pipe joint in no time.