To replace the valve core in a water purifier faucet, first shut off the water supply and open the faucet to drain residual water. Remove the faucet handle using a flathead screwdriver to expose the valve stem. Unscrew the old valve core by turning it counterclockwise with pliers or a wrench. Clean the seat with a vinegar solution to remove mineral deposits. Insert the new valve core into the seat, ensuring it fits snugly, and tighten it clockwise. Reassemble the handle and restore water flow to test for leaks.

Replacing the valve core is critical because a damaged or worn-out core can lead to water leaks, reduced water pressure, and increased utility costs. According to the Environmental Protection Agency (EPA), faulty plumbing fixtures account for 10% of household water waste, costing homeowners an average of $100 annually. A 2021 study by the Water Quality Research Foundation found that 40% of water purifier faucet failures are due to valve core issues, often caused by mineral buildup or corrosion. Regular valve core replacements extend faucet lifespan by up to 5 years and improve water efficiency. The EPA estimates that proper maintenance of plumbing systems can reduce water waste by 30%, saving households $200–$300 yearly. Neglecting this repair may also result in property damage from leaks, as 20% of U.S. homeowners report experiencing water-related damage from undetected plumbing issues. Therefore, proactive valve core replacement is both cost-effective and essential for maintaining reliable water purification systems.