How to Install a Low-Flow Bathroom Faucet

Water efficiency in the bathroom starts at the sink. Old faucets often run at 2.2 gallons per minute, while modern low-flow versions drop that to 1.5 or less, saving thousands of gallons annually without you ever noticing a difference in the stream. Doing this job yourself is straightforward, provided you have the right reach under the vanity. A successful installation results in a leak-free connection, smooth handle operation, and an immediate reduction in your utility footprint. Work methodically to ensure your seals are tight and your supply lines are stress-free.

1. Stop Water Flow First. Locate the shut-off valves under the sink and turn them clockwise until tight. Open the faucet handles to bleed out any remaining water in the lines.
2. Free the Old Lines. Use an adjustable wrench to loosen the nuts connecting the supply lines to the faucet shanks. Pull the lines away from the faucet.
3. Extract the Old Faucet. Unscrew the mounting nuts holding the faucet assembly to the underside of the countertop. Lift the old faucet straight up and out of the sink holes.
4. Bare the Deck Clean. Scrape away old plumber's putty or calcification from the vanity deck using a plastic putty knife. Wipe the surface clean with a damp cloth so the new gasket sits flush.
5. Mount the New Faucet. Place the new faucet gasket over the holes and insert the faucet shanks through the sink deck. Tighten the mounting nuts from underneath, ensuring the unit is centered.
6. Seal the Water Lines. Attach the supply lines to the new faucet shanks and the shut-off valves. Tighten the connections firmly, but do not overtighten to avoid cracking the plastic or rubber seals.