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Toilet Shut-Off Valve Size [Explained]

Shut-off valves are long-lasting.

But when it finally quits working, you’ll be needing an immediate replacement. But the size requirement could be a big problem.

What is the toilet shut-off valve size?

To be fair, there are many types of shut-off valves for toilets. Compression fitting, sweat fitting, PEX shut-off valves are the most common ones. When it comes to measurements, the most common size for shut-off-valve is ⅜” compression. It’s easier to find compatible water supply lines with ⅜’’ shut-off valves.

This isn’t the only information you need.

Read along If you’re curious to find more about toilet shut-off valves!

Without any more delay, let’s begin!

What Is Toilet Shut-Off Valve

Shut-off valves are a type of fitting regulator. It controls and directs the water flow passing through the pipe. It’s used to stop the flow of water inside the pipe once it’s activated.

Shut-off valves in the toilets are called toilet supply valves. Because it controls the freshwater supply from the supply line to the tank. They are also known as stop valves. 

Because turning it off stops the water flow in the supply line. This is why the tank can’t be filled once it’s turned off. They’re installed behind the toilet. Usually, it’s placed beside the toilet rough-in the floor.

Importance Of Right Sized Shut-Off Valve

Toilet Shut-Off Valve Size [Explained] 1

It’s important to get the right sizing for your toilet shut-off valve. Otherwise, there’ll be many plumbing issues to face. You might’ve to deal with a water leakage problem if the sizing isn’t right. Slow water movement is another issue if the pipe has a smaller diameter than required. 

The shut-off valve is attached to many types of PVC connections. These pipes are connected to one another. They must be compatible in size to function properly.

You should gain a rough idea about the pipe sizes in your toilet. It’ll help you to pick the right shut-off valve for your toilet. To get the proper knowledge on this issue, keep reading with us!

Shut-Off Valves Sizing For Toilet

Toilet Shut-Off Valve Size [Explained] 2

Most of the supply line hoses come with 3/8’’, 7/16’’, and 1/2’’ compression. Stop valves also come with various sized outlets. The most common size among them is 3/8’’, 1/4” and 1/2’’. 

It’s better to get a ⅜” shut-off valve when you’re thinking of buying a new one. Because it’s easier to get the necessary tools for ⅜’’ sizing. It also ensures adequate water flow to the system. 

Now, there are different types of shut-off valves for toilets. These valves vary in shape, functionality, and obviously size. This is why it’s important to know about them. 

Here, we’ve mentioned the sizes for some most commonly used shut-off valves:

Compression Fitting Valve

Compression fitting shut-off valves are mostly used for PEX and copper-based water PVC pipes. It’s more adjustable with copper wires. It requires less maintenance and gives more compression power.

It’s usually available in two variants, multi-turn, and quarter turn. These valves are available in sizes of ½” x ⅜” and ⅝” x ⅜”. 

Sweat Fitting Valve

Sweat fitting valves are designed for copper fluid supply lines. They are cost-effective and used during home construction. The installation cost of this valve is cheaper than replacing the main water shut-off valve’s cost.

Interesting, right? 

What’s more interesting is that these are available in different sizes. You can find these valves in ½”, ¾”, and ⅜” sizes. This way you can easily pick one for your toilet.

PEX Shut-Off Valve

Last but not least, let’s get to know about the Pex shut-off valves. These valves are mostly used for pipes that contain clamp rings. Most of them come with ½” x ⅜” size. 

By the way, if you didn’t know, there are two variants of the PEX shut-off valve. One is the Pex clamp shut-off valve and another is the Pex push-fit shut-off valve. 

PEX plumbing materials are cheaper. But before installation, you’ve to size your PEX pipe fitting for home plumbing.

For your comfort, we’ve mentioned a few of the shut-off valves. You can pick any of them:

Product 1
Product 2

These are the most commonly used toilet shut-off valves and their sizes. You can now easily pick the right-sized shut-off valves for your toilet. Because all the mentioned information will surely be useful to you.


Question: How long does a shut-off valve last?

Answer: Shut-off valves last over 8 to 10 years. It’s prone to go bad as it gets old. Sometimes the rubber tears or the seals inside the valve deteriorate. The most common failure you’ll face is valve seizing. This implies that you won’t be able to stop it by using your hand.

Question: Why does a shut-off valve leak water?

Answer: Shut-off valves are rarely used. This is why the washer inside the valve gets jammed with water deposits over the years. When opening or closing the valve might not seat properly on the stem. It leads to water leakage.

Question: Why do ball valves fail to function?

Answer: Ball valves quit functioning when they cross their life expectancy. Usually, it’s 8 to 10 years. They fail due to corrosion’s presence inside the ball valve.

Final Word

That was all from us about the toilet shut-off valve size.

Hopefully, the information is sufficient for you.

See you in another post till then good picking the correct sized shut-off valve!