Manufacturers recommend flushing your tankless water heater once a year. Flushing your tankless water heater at least every so often will keep it running better and longer. This is especially important in the Austin area due to it’s hard water. When neglecting to flush a tankless water heater system, you can expect excessive calcium, magnesium, and other buildup in your system. This buildup causes obstructed pipes, poor performance, and can cause your tankless water heater to fail prematurely.