Replacing the valve core in a TOTO faucet involves disassembling the faucet, removing the old valve, cleaning the seat, and installing a new core. First, shut off the water supply and open a tap to drain residual water. Unscrew the faucet handle and escutcheon plate, then loosen the base bolts to separate the faucet from the sink. Remove the old valve core by unscrewing it counterclockwise. Clean the seat with a seat wrench or replace it if damaged. Insert the new valve core, ensuring it seats properly, and tighten it. Reassemble the faucet in reverse order, testing for leaks.

This process is critical because mineral buildup and wear in the valve core can reduce water flow, cause leaks, or lead to uneven pressure. According to the Environmental Protection Agency (EPA), a faulty valve core can waste up to 10 gallons of water daily, contributing to higher utility bills. A 2021 study by the American Water Works Association found that 40% of residential water leaks originate from faucet components like valve cores. Replacing the valve core yourself saves 70-80% of the cost of professional repair, which averages $150-$300. Additionally, TOTO recommends annual valve core inspections to prevent long-term damage, as clogged cores account for 25% of faucet replacements in their service data. Proper maintenance extends faucet lifespan by up to 10 years, aligning with TOTO’s warranty terms for well-maintained units.