The answer to 'how to maintain water heater' is to perform regular maintenance tasks to ensure your water heater is running efficiently and safely. This includes flushing the tank, checking the pressure relief valve, and inspecting the anode rod. It's also important to monitor the temperature and pressure settings, and clean the tank's exterior and interior as needed.
Proper maintenance can extend the life of your water heater and prevent costly repairs or replacements down the line. Be sure to follow the manufacturer's instructions and safety guidelines when performing any maintenance tasks. If you're uncomfortable or unsure about any of the steps, it's best to call a professional plumber for assistance.