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What Size Water Line to Run to Shower? (Explained)

If you are someone that enjoys a little DIY here and there, then you also know the first learning stages of doing something you absolutely have no idea about can be difficult. So much so that we are bound to make mistakes.

Therefore, in order for us to not do something like that in case of building or fixing something ourselves, there are some rules laid down by the officials to help us do things better ourselves and let everyone know the basics at least.

So, when we are going to make water lines for the shower in our bathroom, we will find ourselves in that predicament. That we need to make this right on the first try otherwise things will get worse.

So, to learn more about the minimum and maximum sizes as well as all the nuances that go into making water lines, keep reading below.

What size water line to run to shower?

When it comes to constructing house structures, almost everything is measured and has standard protocols to follow. In the case of constructing water lines in a house, the same rules are also followed. Furthermore, almost all of the water lines to any shower or tub require a one-half-inch diameter.

There are many specifications that we need to do with the placement and different sizes we need for the plumbing of pipes or faucets and fixtures.

These things elude our eyes due to them being complete even before the house is complete. This is because it gets rather difficult when we are working with such things.

Things will become messy as soon as we make a single mistake. This single mistake can hinder us for days and we will be unable to complete our work or reach the goal we intended to reach while constructing our homes.

The sizes for things such as the water line to run to the shower are mostly fixed and constant in most cases.

The size is almost always one-half inch in diameter. This measurement is taken as fundamental when we are working to facilitate a shower with water lines. So basically, we can say that almost all shower water lines are the same size.

Obviously, there will be exceptions in the case of concept homes or something more grounded like a luxury house that has its custom state-of-the-art plumbing system. However, the case remains the same and the size will not change in almost all cases.

Are all shower water lines the same size?

When it comes to construction, there are many rules and regulations that we need to follow without fail. These are there to make convenience for people of every walk of life. That way we cannot make mistakes while building our dream homes.

That is why we can safely say almost all of the shower water lines are the same size and that is one-half inch diameter pipe, with only a few exceptions.

That measurement is also true for both the cold and hot water supplies. This indicates that temperature does not matter here.

Furthermore, showerheads have this universal thread size in the United States and Canada as well, which is denoted as ½-inch NPT.

What size PEX water line to run to shower?

Cross-linked polyethylene (PEX) pipe is a material that is mainly made of plastic. This particular pipe is specifically used for the supply of water piping system.

It is a special grade product that offers multiple advantages over its other competitors like the PVC and copper pipes. Due to how good the PEX pipes are, they are often used in making the piping system of water supply in premium houses.  

If you were wondering to get this same particular pipe in your homestead, then you would need to know the measurement of a shower water line for example.

In that case, we would need to use 3/8”-inch lines to shower, tub, or even faucets in the bathroom.

Does reducing pipe size increase water pressure in the shower?

No, if we slim down on the pipe size for the shower, there will be no rise in water pressure for the shower. This is rather a misconception that came from the lawn sprinkler industry.

They persistently said that maybe using smaller pipe sizes will make the water move through the pipes under high pressure.

This argument stated that water moves through the pipes past the sprinklers if the pipe got smaller so that it squeezes the water and ultimately meaning that the pressure would stay high for the sprinklers to operate.

Therefore, you can rest easy knowing that you would not need to get high-pressure water if you slim down on the pipe sizes. That is just not how it works.

How to measure the water line size to run a shower?

When it comes to measuring things that we need to create for big structures then we always need to follow rules and regulations laid by the state. In those cases, we cannot just randomly measure something and use that as a foundation.

When it comes to measuring the water line size to run a shower, we know that drain pipes for the shower can be a minimum of 2”. But other factors go into deciding how we measure the water line size. Keep reading below to know more.


Pipe size is determined by rules mentioned in “Nominal Pipe Size” (NPS). The actual measurement of the pipe should be measured that way. So, we need to follow this chart and also take the help of “Engineer’s Toolbox”.


In the case of plumbing there is the Fixture Unit (FU) that is a unit of measure. This unit of measure is based on the rate of discharge time of operation and frequency of the use of a fixture. 

Furthermore, it only works on which it expresses the hydraulic load imposed by the fixture on the sanitary plumbing installation.

A Fixture Unit is not some kind of flow rate unit but rather a design factor on which we would measure the line size to run the shower.

How to run water lines for a shower?

Below is a guide on how to run water lines for the shower.

Gather required tools:

First gather the things here, Pipe cutter, two 3/4- by 1/2-inch copper tees, Propane torch, soldering flux, Lead-free solder1/2-inch copper pipe, and fittings Drill3/4-inch drill bit2-by-4 blocking lumber, Three 1/2-inch male copper or brass male sweat adapters, Plumbing tape, Wrench, and a Shower ell.

Assemble the pipes:

Then the first thing we need to do, is assembling the pipes and fittings that are necessary in bringing the water to the wall behind the shower. You will need to drill ¾ inch holes at the bottom plate.

Install blocking:

We need to install blocking in the wall frame that needs to support the shower valve. We can use a crosspiece of 2-by-4 lumber as a general blocking material.

Prepare the valve:

Next we prepare the valve in a way that we can solder pipes on it using the tools we have.

After that, we will need to wrap plumbing tape around the threads of the adapters. Finally, we screw one into each port and tighten it with the wrench.

Install the elbow:

We finally install an elbow for the shower head and screw it on a crosspiece at the correct height.

Then we connect the shower ell to the top port and the valve. We do this with a length of ½-inch copper pipe and solder that piper to the ell as well as the adapter.

Final Thoughts

The measurement for the water line to the shower is one-half inch. This is a constant among all of the plumbing systems that we can think of. This particular size can be the same for both the hot water and the cold water making no difference between them.