Can You Use 1 1/2 Pipe for Shower Drain?

Many people are replacing an existing bathtub with a walk-in shower as a home renovation project. While these projects are usually straightforward, they can also have unforeseen issues.

One of the principal factors you should consider is the drain pipe used. Usually, a bathtub has a drain pipe that’s around 1/2 inch.

If you’re planning on using a 1 1/2 inch pipe for your shower, you must first check your site’s building codes to ensure that it’s not prohibited. A full 2 inches is the standard to ensure the water flows smoothly.

Below are some reasons why you can’t use a 1 ½ inch pipe for your shower drain and the steps you can take to install it properly.

Can You Use 1 1/2 Pipe for Shower Drain?

You cannot use a 1 1/2 pipe for the shower drain. Before starting a project, it’s essential to understand the type of pipe installed in your shower. It will allow you to ensure that the tube works appropriately and prevents it from getting stuck.

Other essential factors that you will consider are the line’s location and how you will set it up.

Prohibited in Most Regions

One of the most significant issues with installing a 1 1/2 inch pipe in a shower is the building codes in most areas. It is because it can be inefficient and requires much upkeep. A perfect setup is also vital to ensure the water flows correctly.

Make sure you choose something legal if you plan on having a 1 1/2 inch pipe for your shower drain. It is one of the biggest concerns people have when installing pipes.

When selling a property, it’s essential to avoid breaking the law and getting a rejected inspection. Also, keep in mind the building codes when it comes to selling.

Reduced Water Flow

Although the 1 1/2′′ pipe will work, experts do not recommend it for use in areas with a reduced water flow. This type of pipe is not ideal because it is typically inefficient. It can cause issues and blockages, and it can also be dangerous.

A 2″ pipe is a good choice for your shower drain. It will allow you to keep the water moving and keep it clean.

Expanded Maintenance to Remain Functional

The purpose of a shower drain is to allow water to flow out of the tub as quickly as possible. You don’t want to have a clog that can take hours to remove, and you don’t want to spend money on repairs.

Due to the increasing number of homeowners, they are now more aware of the type of pipe you should install near their shower drain. It ensures that they can avoid costly repairs in the future.


Having a 1 1/2′′ pipe for your shower drain is inefficient. A 2-inch pipe is the better choice.

The main reason why a shower requires a 2-inch drain is that it allows the water to flow correctly and doesn’t require you to check the entire area constantly. It eliminates spending a lot of money on maintaining the whole bathroom.

Also, by having a 2-inch drain pipe, you can focus on enjoying long showers in your bathroom.

Dangers of Bending the Building Codes and Rules

If you plan on breaking the rules, then you must be ready to accept the consequences.

When an inspector discovers that your work is not in compliance with the code, then you may have to tear it down and redo the work that you have done. You could also face fines and penalties.

A home inspection can reveal discrepancies that could affect the sale of your property. If the buyers don’t find the home complies with the codes, they may leave.

If you have a smaller drainpipe, it might be problematic and require regular service or repairs. It could also add to the cost of the project.

Since building codes enforce strictly, we don’t advocate for people to skirt them. However, if you can’t get a waiver from the inspection department, accept the consequences of breaking the rules.

How to Install a Shower Drain in a Pre-formed Base?

When planning on renovating a bathroom, one of the most critical components you should include is a new shower drain.

A drain assembly of various components, such as a compression nut, rubber gasket, and drain body, will set you back around $7 to $60 at your local hardware store. The piece you will attach to your shower pan should also be fiberglass.

You’ll need to make some pieces of plumber’s putty to seal the drain assembly and the shower pan. To do so, roll the mixture into a half-inch bead and then wrap it around the drain body flange. Press down firmly to form an even seal.

For this step, you will need to place the fiber and rubber gasket on the drain body of the shower pan. After inserting the drain nut, use a pair of adjustable wrenches or pliers to tighten it down. You can also remove any excess adhesive from the top of the drain by using your index finger.

To properly lower the shower pan onto the base of the shower, you need to get a buddy to help you. The shower base is the substructure of the entire shower. It features a drain hole located in the middle of the drain body.

You can also position the drain pipe in the center of the hole to prevent it from dislodging. After making the necessary pieces, take the compression nut and insert it into the hole connected to the drain body. Be sure to position it in the space between the pipe and the drain body.

After securing the compression nut, tighten it with a screwdriver and insert a compression wrench into it. You can then slide the drain cover or strainer onto the drain body.

Frequently Asked Questions

Does a Shower Drain Require a Vent Pipe?

A vent pipe is needed to allow the water to escape from the shower. Without it, the water would not be able to move fast enough and effectively. The water flows freely into the sewer system or septic tank with a vent pipe.

You can always ask your trusted plumber or a local professional to construct or renovate your bathroom to ensure its overall functionality.

What Is the Perfect Pipe Size for a Shower Drain?

The standard size for the most common type of shower drain is 2 inches. It ensures that all the water will go away and prevents the pipes from restricting water flow. An oversized tube would take a long to remove all the water, while a smaller line would limit the flow.

Please make sure that you check out the building code of your area so that you can follow them and not cause any trouble.

How Many Gallon-Per-Minute Can a 1 1/2 Inch Drain Pipe Handle?

When you get a new drain pipe, you might want to know how much water it can drain in a minute. Knowing the correct amount of water that can go through a drain pipe will help you understand its efficiency.

A 1 12-inch pipe with a half-full flow rate of 4.9 gallons per minute is generally considered a good pipe. However, it can also fluctuate due to the type of pipe and its material. For instance, if you use a PVC pipe, the half-full flow rate would be around 8.3 gallons.


So can you use a 1 1/2 pipe for the shower drain? No. If you’re planning on using a 1 1/2 inch pipe for your shower, ensure that your building codes do not prohibit it. A full 2 inches is the standard for smooth water flow.

It may not make sense to require an enormous drain on a shower, but it’s also possible to understand the physics behind the requirement in building codes. Understanding the water flow in a drain can help reveal the reasons behind specific building requirements.