Changing a Delta faucet in a kitchen sink should take only an hour or so, as long as you're prepared. The biggest problems you might encounter are corroded or difficult-to-reach nuts under the sink. Having the proper tools will speed the process no matter what challenges you may encounter when removing the old faucet. Installing the new faucet is usually a much quicker process. The faucet you purchase will have detailed installation instructions, so be sure to read them carefully as well.
Removing Old Faucet
Turn off the water at the shutoff valves under the sink. Alternatively, turn off the water at the meter where water comes into your house. This is usually in the basement or a crawl space. Turn on the faucet to drain any remaining water in the water lines.
Locate the mounting nuts on the faucet. Use a flashlight or work light to see what size nut you are working with, if necessary.
Remove the mounting nuts holding the faucet to the sink, using a basin wrench or channel lock pliers. If the nuts don't come off easily, spray a small amount of penetrating oil onto each nut to loosen it.
Remove the water supply lines from the hot and cold faucet shanks, using an adjustable wrench or basin wrench. The supply lines will be made of either copper or flexible tubing.
Lift the old faucet out of the sink. Set it aside or discard it.
Installing New Faucet
Scrape any caulk off of the sink top and from underneath the sink. Thoroughly clean the sink top with an all-purpose counter cleaner.
Place the gasket that came with the Delta kitchen faucet into position over the holes on the sink. Place the faucet on top of the gasket.
Thread the mounting nut onto the Delta kitchen faucet from underneath the sink. Check the position of the gasket to ensure it's seating correctly between the faucet and the sink. Finish tightening the nut, using a basin wrench or channel lock pliers. Check again to ensure the gasket does not slip out of place as you finish tightening the faucet. Do not overtighten the nuts.
Determine whether or not the existing water supply lines are long enough to reach the new faucet's shanks. If not, measure the distance and purchase new water supply lines.
Wrap plumber's tape around the threads of the faucet's shank. One layer of tape will be sufficient.
Attach the water supply lines to the Delta kitchen faucet. Ensure the hot water line is on the left. Tighten the lines, using an adjustable wrench. Alternatively, use a basin wrench if the shanks are in a hard-to-reach area.
Turn on the water at the shutoff valves or at the water meter. Flush both the hot and cold water lines, checking for leaks under the sink.