To fix a leak in a hot and cold shower faucet, first shut off the water supply under the sink. Disassemble the faucet by unscrewing the handle and removing the escutcheon plate. Locate the O-rings, seals, or cartridge (depending on the faucet type). Inspect these components for wear or damage. Replace any compromised parts, ensuring they fit snugly. For compression faucets, clean the springs and seats; for cartridge models, replace the entire cartridge. Reassemble the faucet, turning each handle to mix hot and cold water and test for leaks. If leaks persist, repeat the process or consult a professional.

Leaky faucets often result from worn seals or O-rings, which allow water to escape before reaching the showerhead. According to the Environmental Protection Agency (EPA), a single dripping faucet can waste up to 3,000 gallons of water annually, equivalent to the yearly usage of one person. Replacing faulty parts is cost-effective compared to hiring a plumber, with average repair costs ranging from $20 to $50 versus $150–$200 for professional service. Additionally, the EPA estimates that fixing leaks can reduce household water waste by 10–15%, saving households approximately $100 annually. Data from the American Water Works Association (AWWA) shows that 55% of residential water leaks originate in faucets, emphasizing the importance of timely repairs to conserve resources and minimize expenses. Proper maintenance extends faucet lifespan by up to 10 years, as outlined in plumbing industry studies.