Today, we’re going to take you through replacing a sink drain pipe in a wall. We will be focusing on the kitchen sink, but the guide below will help you replace just about any sink drain pipe in your home. Whether you have zero DIY experience at all or you’re a pro, this guide to drain pipe removal and replacement will help you.
Remove the old sink drain pipe by cutting away the drywall to gain access and then cutting the section of pipework away. You can then splice your new pipework into the drainage system with couplers designed for the pipes you have.
Tools Required to Replace Sink Drain
The tools needed to replace a sink drain are pretty minimal, and most may already be in your toolkit:
- Flathead screwdriver
- Multi-tool (optional but handy)
- Box cutter or drywall saw
- Cast iron snapping tool (available to rent, only required if you have cast iron pipes)
How to Remove an Old Kitchen Sink Drain Pipe
Here is a breakdown of removing an old kitchen sink drain pipe and replacing it with a fresh section of pipe. This may sound somewhat scary, but replacing this pipe is relatively simple; here is how to do it.
Removing Kitchen Sink Drain Pipe in a Wall
Gain access to the section of the drainpipe that you want to remove
If you’re replacing a rusted or leaking section, you may need to remove a large area of drywall to locate it. You can do this with the box cutter or a multi-tool.
Remove the drain pipe
Once located, you can remove the pipe. If the pipe is made from copper or PVC, you can do this with a hacksaw or a multi-tool with the correct blade fitted. If the pipe is cast iron, you will need a specialist tool available to hire at many tool rental companies.
Removing Kitchen Sink Drain Pipe Coming Out of a Wall
Accessing the drain pipe
If you want to splice a new section of pipe into an existing drain pipe coming out of a wall, you may still need to remove a section of the wall. This will give you more space to work and make the splice less noticeable when you’re finished.
Of course, removing a section of the wall isn’t always ideal. If there is a screw thread on the pipework close to the wall, you can unscrew this and remove that section. When you replace the pipe, ensure the fitting you use has the same pipe thread, or it is a good alternative to the fitting you unscrewed.
Removing the pipe
Removing this drain pipe is simple. You can cut the existing pipe with a hacksaw or multi-tool just like the one above.
How to Install a New Kitchen Sink Drain Pipe in a Wall
Once the old drain pipe is gone, you can install the new section. The most cost-efficient pipe to use is PVC. It is also the easiest to install. PVC pipe can connect to pre-existing metal pipes with transitional connectors, here is how to do it.
Identify the fittings you need
If you are connecting PVC pipe to PVC, the fittings you need will be the same as the ones present already. If you are splicing in PVC to copper or cast iron, you will need transitional fittings with a rubber coupling and stainless compression bands. These are widely available in most hardware stores.
If you are replacing the entire P-trap and the tailpiece, you can buy these ready to install. As you are already replacing the drainpipe, it is worth replacing the P-trap and the tailpiece too. It will refresh the pipework and keep everything in good order. Plus, these pieces won’t take too much money out of your wallet, and they take no time to install.
Replacing the drain pipe
The new pipe should be the same internal diameter and length as the old pipe. This ensures that the drain will function correctly. When connecting the new pipe to an existing drain pipe, place rubber couplings on either end of the existing pipe; loosening the steel bands will help you do this. You can also ease the steel bands on the opposite side of the couplings, ready to receive the new PVC pipe. You can use a flat screwdriver for this, but you can use a 5/16 inch socket if you have one too.
If you are also installing a new tailpiece and P-trap, install all of this before the pipework. Once this is installed, you can take accurate measurements for the rest of the system.
Lift the new pipe into place
Measure and cut the new PVC. You can use the old section to measure this pipe and lift it into place. Place the rubber couplings over the PVC pipe and tighten them for a secure fit. If you are replacing the drain pipe up to a fixture, the sinkhole in the kitchen sink, for example, you can replace the P-trap simultaneously.
If you are installing PVC pipe directly to PVC, the method is similar. However, you will need to use PVC cement to secure the fittings and the pipe in this case. Start with the fittings (the sink drain and P-trap) and secure them in place. You can then take an accurate measurement for the length of pipe you need and manoeuvre it into place.
Supporting the new pipe
The newly installed pipe must be secure. You can use plastic pipe hangers or plumbers strapping to secure the pipe. It’s best if you did this every 4ft. While you may not have replaced 4ft of pipe here, it is worth doing for security and safety if you can add a strap to the pipe. PVC cement takes 30 seconds to begin to bond, but the joints will need about 20 minutes to harden fully. So, handle the new piping with care until it is dry.
It is worth testing the new drain pipe before you cover up any access holes in the wall, as it will be much easier to fix leaks now rather than later. If there are no leaks and the pipework is sound, you can patch the wall, give it a coat of paint and mark the job as a success.
We’re sure you still have a few questions about sink drain pipes. So, here are some FAQs about drain pipe repairs and replacements that we couldn’t fit into the instructional part of this article.
How much does it cost to replace a sink drain pipe?
Replacing a sink drain pipe can cost from $100 – $350 when a professional comes in to do the work. If you replace the pipework yourself, it will cost around $30 – $50 at most for the pipe, fixings and PVC cement, and it will take a few hours to complete. As the material cost is so cheap, it is well worth investing in a multi-tool for this project. You can use it to cut the drywall and the pipe in this project alone. However, its uses around the home are nearly limitless.
How is a sink drain pipe measured?
The drain pipe on a sink is either 1 ¼ or 1 ½ inches in diameter. Most modern sinks have 1 ½ inch pipework as it can accommodate a faster flow of water.
What is the best pipe for a sink drain?
PVC pipe is the best pipe to use in most plumbing applications. It is very strong and doesn’t deteriorate over time like copper and other metals. PVC pipe is also the cheapest option, and there are loads of couplers and fittings available for it, which can bridge the gap between a PVC system and metal piping.
Replacing a sink drain pipe is as simple as removing the old pipework and attaching the new pipes using couplers. When cutting the PVC pipe to length, some care needs to be taken, but it is also nice and cheap. It is worth grabbing a few feet extra while at the hardware store, so if you make a mistake, you have plenty of PVC to get it right the next time.
Installing the new pipework is very straightforward too. Once you know the fittings you need (looking at your existing pipework will help you with this), it’s simply a case of removing the old and threading or cementing on the new. Then you can tidy up, patch the drywall if you needed to gain access to the wall cavity and admire your work.