How to Hook Up a Drain Line to a Sink
After you have attached your faucet and water supply and set your sink, it’s time to connect the sink drain. Drain kits come in different materials and configurations, but installing them is a snap. Choose the kit with the configuration for your sink type, and you’re halfway home!
You have a couple of choices for drain kits: chromed metal kits and PVC drain kits. Both work well and are about equally easy to use. The main factor on deciding which one to use is cosmetic — will the drain line be visible? If it will be visible, you’ll want to use the chromed kit. If it’s out of sight in the sink base cabinet, which most kitchen drains are, then the good-old white plastic PVC kit is the way to go; PVC is cheaper.
Kitchen sink drain kits, whether they’re chromed or PVC, use nut and washer screw-together connections. Besides being easy to install, they also let you easily disconnect the assembly when it’s time to unclog a drain or quickly rescue that wedding ring that fell down the drain. A basic, single-bowl kit includes
A tailpiece, which connects to the bottom of the sink strainer
A trap bend (or P-trap), which forms a water-filled block to prevent sewer gas from coming up through the sink drain
A trap arm, which is connected to the downstream end of the P-trap and then to the drain line that leads to the main drainage line
A double-bowl drain kit will have everything the single-bowl kit has along with a waste-Tee connection and additional length of drain line to connect both bowls to a single P-trap.
If your sink has a garbage disposer, you need an additional longer section of drainpipe to connect the disposer’s drain line to the bowl drain line. The crosspiece that comes in the kit may or may not be long enough to make the connection between the disposer and other sink bowl drain pieces. You have to check yours out to be sure. Follow your disposer’s installation instructions.
Assembling and connecting the drain kit is fairly simple. The pieces are easy to maneuver, so you can adjust them to fit almost any setup. Don’t expect the horizontal pieces to be in super-straight alignment with the tailpieces or the drainpipe. The only thing that matters is that they all eventually get connected together.
Start by attaching the tailpiece to the sink drain and tightening the slip nut and washer by hand.
If you have a multiple bowl sink, all of the drain tailpieces should be the same length for an easier installation.
Slip the trap onto the tailpiece and then position the trap’s horizontal piece next to the drain line coming out of the wall.
The horizontal piece must fit inside the end of the drain line. Remove the trap and cut the horizontal section to fit.
Reattach the trap to the tailpiece and into the drain line and tighten the slip nuts and washers.
Before you do anything else, get the bucket and rags ready. Lay some rags directly below each connection so that, if there is a leak, the towels will immediately soak up the water. And leave the rags there for a couple of days, just in case a leak develops over time.
Have your helper turn on the water while you begin inspecting for leaks. Don’t be alarmed (or upset) if you have a joint that leaks. Just shut off the water, take a deep breath, disassemble and reassemble the connection, and check again for leaks.