Install a New Kitchen Faucet

Replacing a kitchen faucet is one of those projects that looks more complicated than it actually is. A leaky faucet, a handle that's stuck, or simply wanting an upgrade—whatever the reason, this is a job you can handle in an afternoon without calling a plumber. The real work happens underneath the sink, where you'll disconnect the old supply lines and fasten the new body in place. What separates a clean install from a frustrating one is organization: label your lines, take your time under the sink, and don't force anything. A new faucet transforms how a kitchen feels every single day, and you'll know it was installed right when water flows exactly where it should and nothing drips.

1. Kill the Water Flow First. Locate the shutoff valves under the sink, typically a pair of small oval handles on the supply lines coming from the wall. Turn both valves clockwise until they stop—don't force them. If valves don't exist or won't turn, shut off the main water supply to the house. Open the faucet at the sink to release any remaining pressure in the lines.
2. Label Before You Disconnect. Place a small bucket under the connection point to catch residual water. Use an adjustable wrench to loosen the compression nut where the flexible supply lines connect to the shutoff valves. Turn counterclockwise by hand once the wrench breaks it loose. Disconnect both hot and cold lines and set them aside. If supply lines are rigid copper, you may need a basin wrench (a small tool designed specifically for this tight space).
3. Extract the Old Unit. Go back up to the sink and locate the fastening nuts or bolts holding the faucet body in place. These are typically under the mounting collar at the back or sides of where the faucet sits through the deck. Use an adjustable wrench or basin wrench to loosen these fasteners. Some faucets have a single center bolt; others have two or three on the sides. Once loose, lift the old faucet up and out of the sink. Clean away any old plumber's putty or caulk from the mounting holes with a putty knife.
4. Seal the Deck First. If your new faucet came with a gasket or deck plate, position it under the mounting holes on the sink deck. Most modern faucets have a rubber gasket that creates a water-tight seal. Align the holes so the faucet body will sit flush against the sink surface. Some faucets use a small amount of plumber's putty under the deck plate—check the manufacturer's instructions for your specific model.
5. Position Through the Deck. From above the sink, carefully insert the faucet body through the mounting holes. Align the mounting studs (the threaded posts coming out the bottom) with the holes. Push down until the faucet base sits flat against the sink deck or the gasket. The supply line connections should now be accessible from underneath the sink.
6. Tighten the Fasteners Evenly. Go back under the sink. Slide the mounting nuts onto the threaded studs and hand-tighten them first. Once snug, use an adjustable wrench or basin wrench to tighten each nut an additional quarter-turn. Tighten evenly—if you crank down one side first, the faucet body can tilt. The faucet should be firm and unable to rock side to side. Don't over-tighten; you'll strip the threads or crack the deck.
7. Reconnect Hot and Cold. Take the hot supply line (marked or the one originally on the left) and thread it onto the faucet's hot inlet by hand first. Once hand-tight, use an adjustable wrench to snug it another quarter-turn. Repeat with the cold supply line on the cold inlet. These compression fittings should be tight enough that no water leaks, but you don't need to muscle them. If your faucet came with new supply lines, use those instead of the old ones.
8. Check for Leaks at Quarter-Turn. Carefully open both shutoff valves a quarter-turn each. Walk to the sink and open the faucet handle slightly. Let water run for 10 seconds—this clears air from the lines. Close the faucet and go back under the sink. Check all three connection points (hot shutoff to line, cold shutoff to line, and both faucet inlets) for any drips. A single drip means the fitting isn't quite tight enough. A steady flow means you need to turn off the water and re-tighten.
9. Restore Full Water Pressure. Once you've confirmed no leaks during the quarter-turn test, open both shutoff valves all the way by turning them counterclockwise until they stop. You should hear the lines filling with water. Wait 30 seconds to ensure full pressure is restored.
10. Test Both Handles Fully. Go back to the sink and test the faucet completely. Turn the hot handle from cold to hot to full hot. Do the same with the cold side. Test the spray head if there is one. The water should flow smoothly without sputtering, and temperature should change gradually as you move the handle. Watch underneath for any signs of water during this full test.
11. Verify No Leaks Remain. Get down and visually inspect every connection point one more time. Dry any moisture with a rag so you can see water droplets immediately if they form. Leave a rag under the sink for the next hour and check it periodically. Even a slow drip will wet the rag and tell you where the problem is.
12. Dispose and Delight. Once you're confident there are no leaks after 30 minutes, dispose of the old faucet, supply lines, and packaging. Wipe down the underside of the sink with a clean rag. If there are water marks or debris, clean them away now while you have good visibility. Your installation is complete.