This deck-mounted birdbath has a built-in 75 watt heater that operates automatically to keep water from freezing down to -20 F. Thermostatically controlled to run only when necessary.  It turns on at approx 35 degrees and off at 42 degrees.  Costs only pennies a day to operate. Cord tucks away during off season. Installation is simple. Easy to clean. Powder coated finish, rust free.