How to Plumb a Double Sink

Adding a double bowl sink is not only a wise investment for any remodel or new installation, but it offers much more utilizable space in a kitchen or bathroom if several people share the area. The plumbing for sink drains comes in brass, steel and PVC. PVC is often easiest to install, as well as the cheapest option. Brass and steel are good alternatives if the pipes will be visible or not otherwise hidden within a cabinet.

Things You'll Need

• Plumber's putty
• Tape measure
• Plumber's wrench (for brass or steel)
• Saw (for brass or steel)
• Teflon tape (for brass or steel)

Instructions

1. Determine the diameter of the drainpipe you will need, depending upon the location of the installation. Bathrooms typically call for 1-1/4 inch drainpipe, whereas kitchens normally utilize 1-1/2 inch pipe.

2. Remove the previous drainpipe if necessary. If you are removing steel or brass drain drainpipes, use a plumber's wrench to remove the slip nuts that connect each piece of the drain system together. (The slip nut is the large nut between the sections of pipe.)

3. Locate the drainpipe in your wall. Note whether the wall drain is centered between both bowls or off to either the left or right side--this will determine the type of outlet drainpipe (the drain that connects directly to the P-trap) required.

4. Measure the distance from the wall drain to the center of both bowls.

5. Measure the height from the wall drain to the pre-cut drain holes in your sink.

6. Install the drains in the pre-cut holes of each sink basin. Apply a thin layer of plumber's putty where the drain touches the sink's surface; this ensures a proper seal and prevents leaking. After the drain is securely in place, remove any excess plumber's putty from around the inside of the sink's bowl.

7. Insert sink tailpieces (or extensions) into both drains and tighten the slip nut to ensure a proper seal. (If necessary, trim or extend these tailpieces or extensions depending upon the height from the wall drain to the bowls.) The slip nuts that come with the drain pieces are compression nuts--make sure that the washers are on correctly with the tapered end of the washers always facing the next pipe.

8. Connect the sink tailpieces into the outlet drain tee by threading the slip nut down onto the outlet tee's threads. (The outlet tee may need to be trimmed or extended, depending upon the distance of the bowls.) Ensure that the center of each side of the outlet tee lines up with the pre-cut drain holes in your sink.

9. Insert the bottom pipe of the outlet tee into the P-trap and tighten the slip nut. NOTE: If there is a drain in the floor instead of in the wall, you will need an S-trap. (Installation is the same for this type of drain system.)

10. Insert the P-trap into the wall drain, threading the slip nut from the P-trap onto the threads of the wall drain.

Tips & Warnings

• If you are using PVC, do not use Teflon tape around the threads--doing so will strip your threading. Only use Teflon tape with steel and brass drainpipe.

• Do not over-tighten the slip nuts that connect each piece of the drain system together.