If your water heater is in a garage or a non-finished basement where leaking water would flow harmlessly into a drain, a drain pan is not necessary. However, if the heater is in or above a living space where leaking could cause extensive water damage, it is highly recommended to use a drain pan to prevent or minimize property damage. Pans should be plumbed to a proper drain or to a safe disposal area. Drain pans are available in various diameters to accommodate all size water heaters. Pans should be 4" wider in diameter than the diameter of the water heater. Plastic pans should be used with electric water heaters, and metal pans should be used for gas water heaters and can be used with electric water heaters. Codes in some areas require metal pans for all heaters installed in a living space.