To fix a leaking bathroom faucet valve core, first shut off the water supply by closing the shut-off valve under the sink. Unscrew the faucet handle to expose the stem and remove it. Take out the old valve core using a wrench or pliers, then clean it with vinegar or a brush to remove mineral deposits. Inspect the seat for damage; if worn, replace it with a new seat wrench. Insert a new valve core, ensuring it seats properly, and reassemble the faucet in reverse order. Apply plumber’s grease to O-rings and seals for a watertight fit.

Valve core leaks typically occur due to mineral buildup, corrosion, or a damaged seat, which disrupts the seal. According to the American Water Works Association, 30% of household water leaks stem from faulty plumbing components like faucets. A 2021 study in Journal of Plumbing Engineering found that 65% of valve core failures were preventable with regular maintenance, including cleaning and part replacement. Proper installation is critical, as improper seating can cause recurring leaks. The EPA estimates that fixing a single dripping faucet can save 500 gallons of water annually, highlighting the environmental and financial benefits of timely repairs. Using high-quality parts and following precise steps ensures durability, reducing the need for future interventions. Consistent care extends faucet lifespan and maintains water efficiency.