Step 6 · Connect Water Supply and Drain Lines
Now, connect the plumbing. Attach the flexible water supply lines from the faucet inlets down to the corresponding hot and cold shutoff valves. Hand-tighten the nuts, then use a wrench to give them an additional quarter- to half-turn. Do not overtighten. Next, assemble the P-trap. Connect the tailpiece extension to the bottom of the sink's drain assembly if needed. Attach the P-trap to the tailpiece and the drain stub-out in the wall. The slip nuts on the P-trap are designed to be hand-tightened only. Ensure all gaskets are properly seated before tightening.