What Drain Pipe Size To Use For The Bathroom Sink?

If the time has come for you to replace the drain pipe in your bathroom sink, you might be struggling with which size pipe to get for the replacement. Luckily, I’m here to help.

You should use a drain pipe that is the same size as the drain hole in your bathroom sink. The standard drain hole size is 1.25 inches (3.18 centimeters), although some sinks vary in size.

What Drain Pipe Size To Use For The Bathroom Sink?

Keep reading to discover how to select the right drain pipe size for your bathroom sink.

I’ll also answer some frequently asked questions regarding bathroom piping. Let’s get started!

* This article may contain affiliate links. As an Amazon Associate, I earn from qualifying purchases.

How To Choose the Right Pipe for a Bathroom Sink

Getting the right pipe size is essential to preventing water spillage and ensuring that your sink works as well as it possibly can.

Getting the right pipe size for your bathroom sink is a relatively simple part of the bathroom renovation process.

For the best results, you should measure the size of your drain hole in the bathroom sink, although you’ll probably be fine if you get a pipe that is 1.25 inches (3.18 cm) because this is the standard size in most homes.

Some bathrooms have a hole of 1.5 or 1.625 inches (3.81 or 4.13 cm), so I recommend measuring first.

Here’s how to measure your drain hole size:

  1. Apply a lubricant to the old drain pipe.
  2. Use a wrench to detach the pipe from the drain hole. I recommend this WORKPRO 2-Piece Adjustable Wrench Set from Amazon.com because the wrenches are made with high-quality, durable material that will last you a long time. I also like that the wrenches have a corrosion-resistant black finish and precise measurements in both inches and millimeters.
  3. Hold the sink drain steady. I recommend having someone help you during this step so that the sink drain is as steady as possible.
  4. Use a measuring tape to measure how large the drain hole is.

If the drain hole is 1.25 inches (3.18 cm), you can get a 1.25-inch (3.18 cm) drain pipe.

Before you purchase the pipe, you should check the housing code in your state to see if they have specific codes that dictate how large your pipes can be.

Another thing to consider is your water pressure.

A 1.25-inch (3.18 cm) drain pipe can usually handle around three gallons of water per minute, so if your water pressure exceeds that, you may need to get a larger size.

How To Install a Drain Pipe for the Bathroom Sink

What Drain Pipe Size To Use For The Bathroom Sink?
A drain pipe under a sink

Once you have the right drain pipe size, it’s time to install it.

Follow these steps for the best results:

  1. Attach the brass tailpiece to the basket strainer of your sink. Screw the piece on with your hands.
  2. Put the rubber compression gasket in the drain pipe.
  3. Attach the pipe to the brass tailpiece using plumbing tape. I recommend the VOTMELL Plumbers Tape from Amazon because this tape has a sealing function that prevents water leakage and is made of PTFE material, which has high sealing and durability. I also like that each roll of tape is ½ inch (1.27 cm) wide, which is ideal for most plumbing projects.
  4. Use a level to ensure that the pipe is level.
  5. Slide a connector ring up the drain pipe and the brass tailpiece.
  6. Use a wrench to tighten the connector until the pieces are completely sealed. Be careful not to overtighten, which could cause cracks and future leakage.
  7. Test the drainage by turning the sink on.

If you follow these steps and choose the right size drain pipe for your sink, you should have a system that works well and doesn’t leak.

Types of Drain Pipes

Your house has multiple drain pipes that facilitate water movement from one place to another.

Without drain pipes, you wouldn’t have a way of disposing of your wastewater, and if your drain pipes aren’t fitted properly or working as they should, you’ll end up with leakage all over your home.

For a better idea of what size and kind of drain pipe you’ll need for your bathroom, let’s investigate the different drainage pipes and their uses.

1. Polyvinyl Chloride.

Polyvinyl chloride (PVC) pipes are common for drainage purposes.

This material is extremely malleable and can come in almost any size, so they are frequently used in homes, especially where the pipe must deal with a great deal of pressure, such as in a bathroom. This material is also recyclable, so these pipes are more eco-friendly than other alternatives.

2. Cross-Linked Polyethylene.

Cross-linked polyethylene (PEX) is a material made of plastic.

It can handle hot and cold water, which makes it a good choice for bathroom sinks, and it can be retrofitted to copper and PVC pipes, which makes it a more flexible option than other alternatives.

It is also conducive to tight spaces, so if you don’t have a lot of room for plumbing in your bathroom, this material might be a good choice.

3. Acrylonitrile Butadiene Styrene.

Acrylonitrile butadiene styrene (ABS) is similar to PVC and is commonly used for drainage.

It is extremely easy to install because it doesn’t require the solvent coat that PVC piping does, and it is resistant to cold temperatures.

In warm temperatures, this material can warp, which can cause some leakage issues.

You should consult a plumbing professional to find out which pipe is right for your bathroom and plumbing system.

How To Tell if Your Drain Pipe Needs Replacing?

If you’re reading this article, you’ve probably already decided that you’re replacing your drain pipe, and the replacement may be part of a larger renovation.

If you’re on the fence and unsure of if you need to replace your drain pipe or not, the following are symptoms that your drain pipe isn’t working properly and could benefit from replacement:

  • Water backs up in your sink. If you hear a gurgling sound after running the sink and start to notice the water coming back up, this is a clear sign that the draining process isn’t working as it should.
  • The sink drains slowly. If your sink takes a long time to drain completely, you may have something wrong with your pipe. Another possible cause is that something is clogging the pipe. I recommend checking for objects lodged within the pipe before assuming that the pipe needs replacement.
  • There’s a funny smell coming from the sink. If your drain pipe is failing, objects won’t be able to properly flow through and out of the pipe into the sewage system. Therefore, substances will start getting lodged in the pipe, which can cause a foul odor.

If you notice these symptoms, replacing your drain pipe sooner rather than later is better.

If you wait too long, you risk inflicting larger damage on your bathroom and more expense in the long run.

However, these symptoms don’t necessarily mean that your pipe needs to be replaced.

In many cases, these problems signify that your drain pipe needs a thorough cleaning.

Here’s how to clean your drain pipe for the best results:

  1. Pour a cup of rock salt down the drain.
  2. Wait ten minutes.
  3. Flush the drain with hot water.
  4. Put on a pair of rubber gloves. I recommend these Bamllum Reusable Cleaning Gloves from Amazon because they are made with high-quality, latex-free, and phthalate-free material that is sturdy and won’t rip easily. I also appreciate how soft and breathable these rubber gloves are because they are more comfortable to wear than other alternatives.
  5. Mix half a cup of baking soda with vinegar until the mixture becomes a thick paste.
  6. Put the mixture in the drain for ten minutes.
  7. While the mixture sits on the drain, boil some water.
  8. Pour the boiling water down the drain.
  9. Use an old toothbrush to scrub any grime and other buildups in the drain.

If your sink is extremely clogged, I suggest using a drain snake to resolve the issue.

A drain snake allows you to clean out the pipe more thoroughly because it can contour around the bends and pick up any clogs and obstructions.

Stick the snake down the drain and turn it clockwise to pick up the blockages.

My favorite drain snake is this Drainsoon Store Sink Snake Drain Clog Remover from Amazon because the nylon material can withstand up to twenty pounds of blockage without breaking. I also like that it is extremely flexible and can get into the drain’s P-trap, which is where many obstructions occur.

You can often fix the problems with your bathroom sink drain with a thorough cleaning.

However, if you clean your sink and notice these issues, you may need to replace the drain pipe, in which case, it is essential that you get the right size.


For most bathrooms, you should use a 1.25-inch (3.18 cm) drain pipe for the sink.

This size is the standard for many homes in the United States, although you should measure your drain hole size first to ensure that your sink matches this measurement.

The right drain pipe size prevents water spillage and ensures that your sink plumbing works best.

Cheers, tools owners!

Hi there! My name is Jack and I write for ToolsOwner. I have a passion for everything related to tools and DIY projects around the house. You often find me in my workshop working on new projects.