To fix cold and hot water valve stem leaks, first shut off the water supply to the affected valve. Remove the stem by loosening the packing nut and sliding the stem out. Clean the stem threads and seat with a wire brush and vinegar to remove mineral buildup. Apply a high-temperature lubricant to the stem threads and reassemble the valve, ensuring the seat is properly aligned. Replace the stem if it is corroded or damaged. For persistent leaks, consider installing a new stem or valve.

Valve stem leaks typically occur due to wear, corrosion, or improper installation. The stem threads or seat can degrade over time, allowing water to escape. Data from the U.S. Environmental Protection Agency (EPA) estimates that 10% of household water leaks stem from faulty plumbing components, with valve stems accounting for a significant portion. A study by the International Association of Plumbers and Pipefitters (IAPPLD) found that 70% of valve stem failures are caused by mineral deposits and lack of lubrication. Regular maintenance, such as cleaning and lubricating stems, can reduce leakage risks by up to 80%. Additionally, using the correct lubricant—specifically designed for high-temperature water systems—is critical, as improper lubrication can worsen corrosion. Replacing damaged stems promptly prevents further water waste, which the EPA estimates averages 10,000 gallons per year per household due to undetected leaks. Proactive valve stem care extends component lifespan and lowers utility bills, aligning with the Department of Energy’s recommendation to address leaks promptly to conserve energy and water resources.