How to Cap Off a Sink Drain Pipe

Before you start, make sure the water is turned off, and the sink bowl is empty. Next, use a wrench to loosen the nut on top of the drainpipe, where it connects with a P-trap. Now, use an adjustable wrench to unscrew that same nut from below until just before it comes free from its connection point to your home’s plumbing pipes.

Twist this loosened pipe counterclockwise as if you were tightening it back up, but in reverse so as not to undo what has been done so far. With those steps now complete, wait for all water inside every section of pipe outside of your home’s plumbing system to be drained out before proceeding any further. This post is about how to cap off a sink drain pipe.

How to Cap Off a Sink Drain Pipe

Step to Follow on How to Cap Off a Sink Drain Pipe

Step One: Find a Proper Size Cap

A major consideration in capping off a sink drain pipe is finding a cap that fits the existing drain pipe. First, make a few marks on the existing pipe where it comes out from under the sink to find a good fit. Then go to the hardware store and purchase an appropriately sized rubber cap to screw onto the end of the pipe.

Find a Proper Size Cap

It’s essential to make sure that the rubber cap has a small enough diameter that it can be forced onto the end of the existing pipe. If it’s too large, then you should try for a smaller size until you find one that fits snugly and can be pushed onto the end of the existing pipe.

Step Two: Cut the Existing Pipe

After finding a rubber cap that fits onto the end of the existing pipe, use a hacksaw to cut off about one inch from the top of the existing pipe. Next, using a screwdriver, pry off the top of the rubber cap. Make sure that you don’t damage any nearby pipes while forcing off the cap.

This is important because it will expose the top of the existing pipe. If you don’t remove this cap, when you screw in your new drain pipe to connect to the rest of your drainage system, there’s a small chance that water could pour out of your old pipe and onto your feet.

Step Three: Screw on New Drain Pipe

After the existing pipe has been cut and the top of it exposed, screw on a new drain pipe. Use Teflon tape to make a watertight seal between your new drain pipe and the existing one. Then press down all around the rubber cap with your fingers to ensure no small leaks that could contaminate whatever you are draining.

When you are done, you will have successfully capped off your sink drain pipe and prevented any future leaks or damage caused by water coming out of the existing pipe and onto something else. Now you know how to cap off your sink drain piping, so get out there and do it! It’s a great way to prevent water damage.

Step Four: Add a Drain Trap

If you want to make your drain piping system more secure, consider adding a drain trap. A drain trap will help eliminate the possibility of any future leaks or damage by catching and holding water in the existing pipe until it is drained out of the drainage system with the rest of the water from your sink while keeping unwanted materials out of your drain.

Add a Drain Trap

To add a drain trap, you should first shut off the water to the pipes under your sink. Then use any one of several popular methods to attach a flexible tube or pipe to the existing piping system. Once the flexible pipe is added, attach a drain trap to allow water to move through it but not any solids or other unwanted materials.

Step Five: Test for Leaks

Once everything is capped off, and you’ve added a drain trap or flexible pipe, turn the water back on under your sink. Now check around any rubber caps to make sure that there are no small leaks. Doing this will allow you to head off future problems before they happen by catching them early on in the game.

 Paint Your Floor With a Fresh Coat

Now that you understand how to cap off a sink drain pipe, you should try it out. Capping off your existing drain piping system will save you time and money in the future by preventing water damage. It’s well worth the effort to learn how to do this because it could save you hundreds of dollars in repairs or having to replace your flooring, cabinets, or appliances in the future.

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Step Six: Dispose of Cut Pipe

You will want to dispose of the old, cut-off pipe that you cut down to about an inch in length and removed from the rubber cap. If you throw this away, it could end up in a landfill and continue to rust or leak into your floors or cabinets below.

To properly get rid of this cut-down pipe, you should take it to a recycling center for scrap metal. Doing so will prevent any future leaks or damage that could come from the old cut-off pipe and let you know how to cap off your sink drain pipe safely and efficiently.

Step Seven: Paint Your Floor

Once you have capped off your sink drain pipe, it’s time to paint your floor with a fresh coat of whatever color you’d like after all the repairs are done. Doing this will help keep any rust or leaks from ruining your floors or cabinets in the future by making sure everything is properly sealed off and protecting you from unwanted leaks.

Once everything is painted and you know how to cap off your sink drain pipe, you will have an easier time preventing water damage in the future by simply knowing How to Cap Off a Sink Drain Pipe. Keep this information in mind for any future projects where you need knowledge on how to cap off your sink drainpipe so that you can head off any future leaks and damage in the kitchen.

Step Eight: Maintain Your Drain System

Like fixing your sink drain pipes, you will want to maintain your new capping system so that any future leaks are caught early on in the game. Keeping your drain piping system is easy, often requiring only a simple check-up every six months or so.

Maintain Your Drain System

To maintain your capping off of the sink drain pipe, simply turn the water back on under your sink and check around any rubber caps for about a minute or so. If you notice any new trickles or leaks during this time, it’s probably best to call a professional plumber since they will have more experience with fixing leaky piping systems than a novice homeowner would.

You Can Check It Out to: Fix Gurgling Kitchen Sink

Frequently Asked Questions

How Do You Cap a Pvc Drain Pipe?

There Are Two Ways to Cap a Pvc Drain Pipe :

1. Use an end cap that fits tightly into the drainpipe, with a flange at least 1/2 inch above the ground and as close to the edge of the pipe as possible. The other end of the cap should be inserted in a matching opening in your sewer line.

2. Cut off one side of a bucket and slide it over the top of the pipe until it is tight against the bottom of your sewer line.

Can You Cap Off a Sink Drain?

A sink drain is capped off when the water in the sink drains slower than usual.

The main reason why a sink drain may be running slow is because of the sediment buildup that occurs inside the pipe. This can happen when particles such as hair, soap scum, and food debris accumulate in the pipe. If you want to fix this problem, you will need to clean out your pipes using a plunger or a snake (a long tube with a narrow end) to clear out the clog.

How Do You Cap Off Old Plumbing?

There are many ways to cap off old plumbing. One way is by using a cap with a gasket that has been used for years and is also in good condition. Another option is to use a new sealant like PVC primer, silicone, or hot-melt glue purchased at the hardware store.

However, suppose the pipe was recently installed. In that case, you will need to use an expanding foam pipe sealant like the Duragard Sump Gasket, which expands when it comes into contact with water, creating a permanent barrier around the pipe while still allowing water to flow through.

Screw on New Drain Pipe


The most important thing to remember when working on your sink is not to put any water in it. Your goal with installing a new drain pipe for the sink should be that you have an unobstructed path from the top of the overflow tube, through the hole or threads created by removing the old screw or pop-up assembly, and down into the drain line below.

Once everything has been cut off, please give yourself plenty of time before turning on your taps again because it will take some time for all of those gallons of water to make their way out and allow air back in. We hope you enjoyed this article on how to cap off a sink drain pipe.

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