Most kitchen sinks can stand the wear and tear of many years, but the sink drain pipe is another story. Often, drain pipes become clogged, corroded, or just begin to smell so badly they can't be cleaned. The replacing of a drain pipe is a simple procedure which is quite cost effective. All products can be found at the local home improvement store, and PVC drain kits can be found for single or double draining sinks.
Step 1 - Removing the Old Drain
Before working on the sink, turn off the main water of the house. Be aware that some water may still be present in the pipes but will not cause flooding. Rotate the slip nut counter-clockwise (to the left) with the pipe wrench. Once loosened, pull the existing drain pipe away from the sink's main drain.
Step 2 - Preparing the New Drain
Around the smaller sized threads of the sink drain pipe, wrap plumbers or Teflon tape a couple of times. Fit the straight tail pipe into the sink's drain and attach it with the slip nut. Thread the tail pipe in until secure but do not completely tighten. On double drain sinks, two tailpipes will need to be fitted, and then attached together with a T section.
Step 3 - Sizing the Tail Pipe
The P-Trap, or sink trap, should be fitted into place on the tail pipe. If there is not enough space for everything to adequately fit, draw an approximate line on the tail pipe with a Sharpie and remove the piece. Using the hacksaw, cut the tail pipe to fit. Test fit the tail pipe before completely screwing it down or attaching the P-Trap. Once everything fits, screw down the tail pipe.
Step 4 - Attaching the P-Trap
Place the washers into the slip nuts, and the slip nuts on either end of the P-Trap. Be sure the threads on the slip nuts are facing out. Tighten the P-Trap into place beginning at the tail pipe and working down to the main drain attached to the wall. Do not over-tighten the treads, as this will strip the PVC pipe, and it will not be able to be removed if there is ever a clog. Secondly, over-tightening can cause cracking within the plastic treads on the PVC, and leaks will occur. The washers should create enough pressure with one to two turns past fingertip-tight.
Step 5 - Turn on the Water
Turn the house's central water back on and allow the faucet to run at medium flow. Leave the under-sink cabinets open so that any leaking can be viewed. If leaks occur, trace the water back to the source while the sink is still flowing. If water is leaking from one of the slip nuts connections, turn off the faucet and check the internal washers for correct placement or abrasions. If the leak is coming from where the main sink drain attaches, unscrew the tailpipe and view the plumbers tape. Add more if necessary.