How to Install an Under-Sink Filter
Unfortunately, the tap water in some areas leaves a lot to be desired. Fortunately, there's an easy way to resolve this problem: install a water filter.
Remove any burrs off the end of your stub pipes using the reamer on the end of your pipe cutter. Take a 3/4" double compression fitting and slide one nut and ferrel onto your extension pipe. Tighten down the connection to the center compression coupling.
Repeat the steps for the other stub pipe, sliding on the nut and ferrel. Then, tighten it to the compression creating a watertight seal. Attach the soft tubing to the compression coupling by sliding one end of the tubing into the coupling, then tightening it down at first by hand. Tighten with a wrench while backing off with another.
Slowly run the copper tubing across the wall, then to the sink. Repeat this process for the other water line. Don't overbend the pipe or it will crimp and cause a leak.
Use 1/2" copper clips to secure the pipes to the wall. Simply place the clip over the pipe, then screw them in with screws and shields. The LAV stop connects the same way as the water lines. Tighten down the compression fitting to make the seal. Run the hot water line to the left and the cold on the right to match the faucet.
Apply a line of silicon sealant around the edge of the opening. This will hold the sink into place and create a watertight seal.
Place small blocks of wood around the corners of the sink opening. The blocks serve as spacers, keeping your fingers from getting pinched between the sink and the workbench. Finally, put the sink and faucet into place.
Coat the thread of the male adapter with Teflon paste, then firmly tighten it into the old cleanout threads. Glue in a new Y fitting with a cleanout. On the open end of the Y fitting, run your drain line out to the sink area. Make sure to keep a constant pitch for drainage. Connect the water lines from the faucet to the water pipes.
Apply some plumber's putty around the bottom of the flange. Place the strainer in the hole. Attach the rubber washer, fiber washer and locking ring to the underside of the strainer and tighten.
Coat the threads of the auto-vent with Teflon tape and hand tighten into the female adapter. Glue the female adaptor to the middle hole of the Y fitting.
Glue the T-Y fittings with the vent onto the drain line. Ensure the direction of the bend goes toward the drain line. Attach the tailpiece to the sink strainer.
Connect the P trap with the trap adapter to the tailpiece. The final piece of the P trap is a Street-90 that connects the trap assembly into the open end of the vent T-Y fitting.