The answer to 'how to fix water heater' is to diagnose and repair any issues with the water heater. This may involve flushing the tank, replacing the heating element, or addressing other common problems like leaks or sediment buildup. Regular maintenance is also important to keep your water heater running efficiently and prevent future issues.
If you're not comfortable performing water heater repairs yourself, it's best to call a licensed plumber. They have the right tools and expertise to safely diagnose and fix any problems with your water heater.