How to Cap off a Sink Drain Pipe

Is your kitchen sink drain pipe leaking? If yes, you should consider fixing it as quickly as possible. The best way to seal a sink plumbing pipe is by capping it.

Whether you are new to plumbing or handled several plumbing-projects on your own, you aren’t going to have a hard time capping your drain pipe.

Granted, there are different ways to fix a leaking drain pipe, but capping it is the easiest and most effective. Even more, it can help decrease water wastage and increase the durability of your PVC pipe.

Note that capping can also be used to shut off unused sink drain pipes during a kitchen renovation project.

How to Cap off a Sink Drain Pipe

There are two distinct ways to cap off a sink drain pipe. The first method is temporary and should only be used during a renovating-operation or when you want to cap the sink drain for a while.

The second method, which seals the drain-pipes permanently, should be used when the pipe is leaking, and you need to seal it off for good.

Temporary Capping

To cap off unused drain pipe using this method, you will need the following.

  • Measuring tape
  • Rag
  • Emery cloth
  • Hacksaw
  • Marker
  • Pip cap

Before you start, you should ensure that the cap you picked will fit into the drain pipe.

Step 1: Turn off the water supply

Since you will be cutting some pipes during the operation, it is critical that you turn off your water supply. You can do this by switching off your water control switch.

Even if you plan to unscrew the pipe instead of cutting, it is still wise that you turn off the water supply.

Step 2: Cutting the pipe

As soon as you have turned off the water supply, you should use a measuring tape to measure the area you want to cut. Next, use a hacksaw to cut the pipe.

After doing this, use a rag to clean the edge of the pipe to remove debris or dry any water spills. And if the edges aren’t smooth, you should use an emery cloth to carefully sand it down.

Step 3: Installing the cap

This step is pretty straightforward. All you need do is put the cap on top of the open drain pipe and press it down. To ensure that the cap seats well on the pipe, you should measure the length of the cap before starting the operation. If you can pull this off, it will be easier for you to know if the cap is installed properly.

If after a while you want to un-cap the drain, perhaps because you are done renovating your kitchen, here is what you should do. Grab the cap tightly and pull it out. It is that simple.

Permanent Capping

As previously mentioned, this method is great to cap off a PVC sink drain pipe that is overflowing or leaking. This method is also perfect for capping unused drains permanently.

Below are a few things you will need during the operation.

  • PVC cement
  • Wrench
  • PVC primer

Note that this method may take a little bit more time than the temporary one. That said, one thing you can be sure of is that it can seal a drainpipe permanently.

Step 1: Using the primer

Use a cloth to wipe the ending of the pipe. Next, use a PVC primer to carefully coat the outer and inner surface of the exterior cap and the drain-pipe you want to seal-off. The job of the PVC primer is to reduce friction and make both parts stick together.

Step 2: Putting the PVC cement

All have to do here is to put the PVC cement on the cap and the pipe. After you have done this, you should position your pipe horizontally and carefully place the cap on top of it.

Press the cap down and hold it for a few minutes. Next, uses a wrench to tighten the cap (clockwise).

Step 3: Inspect the fixture

To ensure that the pipe is properly sealed and isn’t leaking, you should run a quick test.

Turn on your water supply and watch if the fixture leaks. If it leaks, chances are, you didn’t cap it well. If that is the case, you should consider hiring an expert.

If you were able to cap it properly, a part of you will likely wonder how you are going to uncap it in the future. Uncapping a permanently sealed pipe drain isn’t as difficult as you think. All you need is a hack saw to cut off the cap. Since the cap was glued to the pipe, it will be next to impossible to separate it by hand.

When to Test your Fixture

After capping your sink pipe, you may want to test it as soon as possible. Testing to see if it leaks moments after gluing the cap on it is by no means a good idea.

The reason for this is that most PVC glue takes about 24 hours to dry up. So if you test it during the 24-hour time frame, chances are, it will leak.

Why capping off sink drain pipe is important?

Whether your sink drain-pipe is leaking or it isn’t going to be in use for a while, you should consider capping it quickly. If you do this, you are going to enjoy the following benefits.

Prevents Water wastage

Your water bill is going to increase drastically if your pipe is leaking all day. Capping off your sink drain pipe can help turn things around and prevent water wastage.

Talking about saving costs, you don’t need to hire a plumber to cap off your leaking sink drain pipe permanently or temporarily. All you need to do is to follow the steps above.

Make your renovation process seamless

Before renovating your kitchen or washroom, you may be required to first seal your plumbing pipes. With a cap, you will be able to do this without any hassle and get on with your renovation operation.

Preserve your PVC pipes

If water leaks out of your drain pipes for a long time, its durability is going to reduce drastically. Capping it can prevent it from degrading and make it last longer.


The benefits of capping off your sink drain pipe when it is leaking or not in use are endless.

Of course, there are other methods you can use to address a leaking drain pipe, but most of them are complicated. Even worse, it can only be done by a plumber.

Learning how to cap off a sink drain pipe is by far a better option, as it is easy, convenient, and effective. And remember that you have the option of capping your drain pipe either temporarily or permanently.

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