8 Steps on How to Plumb a Bathroom Sink


Imagine coming home to a flooded bathroom floor and there’s no plumber on hand. When plumbing issues crop up in your bathroom sink, you don’t have to wait for specialist plumbers. With a few how-to guidelines, you can easily do it yourself. However, if you find the task too messy or complicated for you, a plumber would come in handy.

Whether you are replacing an old bathroom sink or installing a new one in your recently constructed home, you can learn how to plan for the task and to install a new sink securely, especially if you are into DIY. Plumbing a bathroom sink is an intricate task. It requires one to be extremely careful to avoid scratching the countertops.

The process of plumbing a bathroom sink varies depending on the brand, but the steps are quite similar. The following is an 8-step process for how to plumb a bathroom sink.

1. Take Several Measurements

If you want to plumb a bathroom sink, you should first measure the width, length and depth of your current sink. When installing a new sink, determine the size by first measuring the width of the countertop. Next, measure the distance between the countertop’s edge, and where the sink’s edge will be after installation, and the distance from the wall to where the back of the sink will be.

2. Turn Off the Water

Once you have all your tools in place, cut off the flow of water to your bathroom sink, from the main shutoff valve located under the sink. Verify it’s off by turning on the old sink’s faucet. If there is no water, it means the main shutoff valve is closed. Make sure you have a rag, mop, and a bucket to deal with water spills.

3. Remove the Old Drainpipe

Disconnect the drain, which is located under the sink. Each section of the pipe is connected with slip nuts. If the drainpipe is made out of metal or brass, disconnect it using a plumber’s wrench. Disassemble the pop-up stopper mechanism, the P-trap, or anything attached to the drain before disconnecting it.

The P-trap is connected to the sink’s tailpiece, the pipe that vertically extends into the drain. Using your hand or adjustable pliers, disconnect it by loosening the P-trap compression and pulling it down. The pop-up stopper is disconnected by sliding the U-shaped spring towards the far end of the arm, then removing it.

4. Remove the Old Sink

Most sinks have clips underneath, which create a pressure connection between the sink and the underside of the countertops. To remove the old sink, loosen them using a screwdriver or by hand. Next, use a utility knife to cut through the sealant between the countertop and the sink. Carefully run the knife’s blade between the sink’s rim and the countertop.

The next step is to lift the sink from the countertop with a little push from below. Be extra careful when removing the sink from the countertop, especially if the countertop is made of laminated wood. This way you won’t destroy the countertop by erroneously cutting it when replacing the sink without changing it. Otherwise, simultaneously replacing the sink and the countertop is much easier.

5. Install Faucet and Drain on New Sink

Install the drain and faucet onto the new sink first, then insert it into the countertop. If both the drain and faucet of your old sink are in good condition, you can re-use them.

Otherwise, buy new ones to go with the new sink. Should you be unfamiliar with this kind of project, purchase a new drain and faucet since it always comes with an installation manual. Because the installation varies from brand to brand, anyone interested in DIY can do it. Better still, you can contact a plumber if you find this task too complicated.

6. Caulk the New Sink

To begin the caulking process, turn over the sink and place it on a towel. Next, apply a 1/4-inch of caulk underneath the rim. However, before you apply plumber’s putty or caulk to the new sink, ensure the brand is safe and compatible with your chosen countertop. Surfaces made from granite, or any other fine material, get ruined when the wrong type of caulk is used.

7. Install the Sink

Carefully lift the sink and drop it into the opening. After the new sink is in place, firmly press down around the edges and wipe off the excess caulk that squeezes out using paper towels. Finish this part of the process by reinstalling the clips.

8. Reconnect the Water Lines

To reconnect the water lines, connect the drain assembly first. Next, reconnect the supply lines to the faucet’s tailpiece. Finally, attach the stopper, the trap and the tailpiece. To be sure the connections are secure, turn on the water and look out for leaks.