What Is The Purpose Of Plumber’s Tape?

Teflon tape also known as plumber’s tape is a polytetrafluoroethylene film tape (a word you won’t have to remember) and something that is very important in a plumber’s arsenal.

So what is the purpose of teflon tape? Teflon tape allows a plumber to provide an extra thin layer of material that can form to the threads of pipe and fittings. This thin layer of material acts to provide a water tight seal for drainage, water and gas applications.

It’s true. A lot of the plumbing run in your home, office, church or wherever uses teflon tape to provide a water tight seal.

This material is very easy to use and there’s a lot more to learn about it, so stick around to learn more!

What Is The Purpose Of Teflon Tape?

Teflon tape has been in use now for many years and is used across multiple different trades. This inexpensive, easy to use material usually comes in a pink color but can be seen in white or yellow as well.

In plumbing, there are many times where the requirement of a glued or soldered fitting just doesn’t make as much sense as using a connection that involves threads.

What Are Threads?

Threads are essentially the part of a fitting that enables the ‘screwing’ on of another fitting or nut. A great way to think about it is a water bottle cap. The inside of the cap has threads as well as the outside of the top of the bottle.

There are male threads and female threads. A male thread would be the top of the water bottle and a female thread would be the inside of the cap.

Both must be machined to precision to allow this connection to work. Threads work in such a way that the further down the threads you go, the tighter the connection will become.

The tighter the connection, the better the fit. However this is not always the case when you’re dealing with things like pressure.

In a water supply system, teflon tape may be added to a connection where this is no rubber gasket. The purpose of the rubber gasket is to provide the water tight seal as the threads are tightened.

When there is no rubber gasket, that’s when the teflon tape can come into play. Teflon tape can be wrapped around the outside of the male threads and usually only requires to go around about two times.

This layer of tape allows for threads to still pass over with relative ease, but forms to it’s shape and provides a space cushion that gives water nowhere to escape.

The same can be true in gas systems. Where ever connections are made via threads, teflon tape will be used to prevent any gas from escaping.

When Is A Threaded Connection Used?

Threaded connections are great for areas of plumbing where repairs, replacements or removals may be more common.

Typically the plumbing in your home is pretty set in stone, and to remove it may require you to rip down dry wall and cut it up. If it’s water supply, it would mean shutting down the water to the whole house, draining the water and then removing the piping etc.

Threaded connections are great for area’s like the water supply connections for a kitchen or bathroom faucet, your shower head, the water connections to your water heater and even your p-trap under the sink.

Places that include a shut off valve are most ideal. When dealing with a kitchen sink, if you want to repair or replace it, you don’t have to shut the water down to the entire house, you can simply turn valve off and undo the connection.

P-traps typically come with a plastic washer that blocks water from your sink from leaking out. This washer sometimes can fail or crack rendering it useless, and teflon can actually be applied around the threads of the fitting to create that desired seal.

Why The Different Colors?

Different colored teflon tape indicates where it should be used. Yellow teflon is gas-rated and has a thicker wall to it with a resistance to gas.

The yellow in a gas system is to help indicate that it is in fact gas. It helps to color co-ordinate things and keep things consistent as yellow is typically the color you are going to see for anything gas related.

You should definitely not ever use plumber’s tape (white or pink) on a gas system, n’or should you even attempt to operate on a gas system without a license, knowledge and expertise. Plumber’s tape, over time will degrade with gas and cause leaks to occur.

White colored teflon may be used in more aesthetic pieces like shower heads or kitchen faucets so as to not stand out as much. You will even find white teflon a lot of the time when you purchase a faucet or shower head etc.

White is typically the thinnest of the tapes and is an adhesive (as well as yellow).

Pink teflon tape is what I have personally used the most in the trades. We always carried our own supply with us wherever we went and just didn’t use the white teflon as we felt it didn’t provide as much integrity.

Can You Have Flames Around Plumber’s Tape?

Plumber’s tape can be used in a variety of different situations for a few different purposes. In some cases you may need to apply it to a thread that has a soldered connection close to it.

Soldering is the process of heating up a metal with a low melting point that can be attracted to flux paste. When a copper fittings end is sand papered down, and flux is applied to both copper pipe and fitting, the flame will draw the solder in towards the inside of the fitting creating a solid water tight seal.

It’s best practice when working around solder to make sure you solder your connection prior to having it come in contact with teflon tape.

For example – On a water heater, the water supply connection is threaded and requires plumber’s tape to create the seal. Sometimes you can get away with using PEX to connect to this fitting, but there are many homes today that still use copper.

When you heat up copper pipe to fit on the opposite side of the threads for the water heater, you can actually melt the tape enough to render it useless.

The best way to go about a situation like that is to cut a piece of copper pipe about 7 inches, solder it to the fitting before hand, let it cool off, apply the teflon to the threaded connection on the water heater and then thread the fitting and pipe to it.

I always recommend to call a licensed professional if you are inexperienced or unsure of what you are doing. These professionals deal with this type of thing on a routine basis and can best assist you. When dealing with soldering, you are dealing with flames, along with water piping among other things. There is potential for burns, leaks, water damage, fires and more.

Teflon tape is designed to withstand temperatures from -200 celsius on the low end up to +260 celsius on the hot end. With flames from a smaller propane torch getting up to just under 1100 celsius it is no wonder why you need to keep the two separate.

How To Properly Apply Plumber’s Tape

Applying plumber’s tape to a fitting may sound really simple, but in fact it is something that is commonly done incorrectly.

When wrapping tape around a thread, if you’re applying it in the wrong direction you may end up with it just bunching up as you try to make the connection of the fittings.

Applying the tape to a fitting can actually be super simple stuff – If you know the how’s and why’s.

First thing you are going to want to make sure of is that you are wrapping the thread in a clockwise direction when the pipe or fitting is facing you.

This ensures that when you tighten up the fitting (righty tighty, lefty loosey) that the fitting will spin in the same direction as the tape as opposed to against it. Wrap the tape around the threads about 2 times to a maximum of 3 times.

If applied incorrectly, and it begins to bunch up it can create sealing issues and render it virtually useless.

*Pro tip – The easiest way to hold the roll of teflon tape is so that, when you’re looking at the very end of the tape, you want the outside of the tape to make contact with the threads. When you spin it in this direction you give resistance to the roll of plumbers tape making it easier to apply to the fitting.




Tyler Takacs

My name is Tyler, I live in Ontario Canada and enjoy learning about common plumbing issues in the household. I have spent just over three years in the trades as a plumbers apprentice, but am now onto a less physical job. I still enjoy studying and learning about my own house's plumbing as well as finding ways to help others with their issues.

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