How to Replace Kitchen Faucet Supply Lines

Supply lines are the unsung heroes of your kitchen plumbing, silently carrying water from your home's main lines to your faucet. Over time, the rubber seals inside these hoses harden or the braiding begins to fray, leading to small, persistent leaks under your sink that can rot out your cabinet base if ignored. Replacing them is a straightforward job that transforms a potential water disaster into a secure, worry-free system. When done well, the connections will be hand-tightened with a slight final turn to ensure a watertight seal, giving you the peace of mind that comes with knowing your plumbing is rock-solid and leak-free.

1. Kill the Water Flow First. Locate the shut-off valves under your kitchen sink and turn them clockwise until they stop. Open the faucet handles to release the pressure remaining in the lines.
2. Unbolt the Old Supply Lines. Use an adjustable wrench to loosen the nuts connecting the supply lines to the shut-off valves. Then, loosen the top connections attached to the faucet tailpieces.
3. Scrub and Clear Mineral Buildup. Remove the old supply lines completely from the cabinet area. Clean any mineral buildup off the shut-off valve threads using a stiff wire brush or a scrub pad.
4. Verify Sizing and Length Match. Compare your new supply lines to the old ones to ensure the length and fitting sizes match. Standard kitchen faucets typically require 3/8-inch compression fittings.
5. Connect New Lines Hand-Tight. Thread the top of the supply lines onto the faucet tailpieces and the bottom onto the shut-off valves. Hand-tighten all connections first to avoid cross-threading.
6. Tighten and Test for Leaks. Use your wrench to give the nuts a final quarter-turn to snug them down. Slowly open the shut-off valves and check every connection for signs of moisture.