Customer had issues with drain and kitchen sink, toilet upstairs and widespread lavatory faucet upstairs. Diagnosed situation found thermal expansion tank, not functioning and causing excess pressure on system. Water heater is approximately 13 years old and so is the pressure valve. Pressure valve tested OK but original to home. Gave estimate for necessary replacements and preemptive ones. Replaced basket strainer on right side of kitchen sink. Use tablets in toilet upstairs tank to show flapper is holding.