A water softener's drain must not connect directly to a home's drainage system without an air gap between the end of the water softener's drain line and the home's drain system. The air gap eliminates the possibility that a negative pressure in the water softener will suck sewer water into the softener's storage tank. If a break occurred in the water-supply pipes, the negative pressure created from the water flowing out of the softener's tank pulls whatever the drain line connects to into the tank. Water softeners need a drain line installed for the tank's routine maintenance.
Remove the water softener's 3/4-inch drain plug, usually located near the water intake pipe. Turn the plug counterclockwise with an adjustable wrench until it spins freely, then spin the plug with a hand.
Cover the water-softener drain fitting's last three threads with a pipe thread compound or plumber's tape. A water softener's drain fitting has threads on its 3/4-inch side and ribs on its 1/2-inch side.
Position the drain fitting's threads against the water softener's drain hole and twist the fitting clockwise. Hand tighten the drain fitting.
Twist the drain fitting one full turn clockwise with the adjustable wrench. Do not over tighten the fitting.
Locate a suitable code-approved drain opening, using local building codes as a guide. Many water softeners dump waste water into a clothes-washing machine's drain pipe, while other water softeners use a floor drain. Some homes are pre-plumbed for a water softener and use a 1/2-inch pipe penetrating the wall near the floor as a water softener drain connection.
Push the end of a 1/2-inch braided drain tube onto the water softener's drain fitting. Push the end of the tube onto the 1/2-inch end of the drain fitting until it passes the ribs and butts against the back of the 3/4-inch side of the fitting. The rib locks the tube in place.
Run the tube to the suitable drain opening and cut the tube to size with a knife. If the end of the tube slips into a clothes-washing machine's drain, extend the drain 8 to 12 inches down the drain opening. If the tube connects to a pre-plumbed drain pipe, force the end of the tube over the drain pipe's fitting until it passes the pipe fitting's ribs. If the water softener's drain tube dumps into a floor drain, run the tube to the floor drain.
Secure the water softener's drain tube with pipe hangers. Mount the pipe hangers to the wall or floor every 2 to 4 feet with screws. The type of screw depends on the wall or floor's material. Generally, drywall screws work on walls and wood floors. Concrete or tile floors need a pilot hole drilled and a concrete screw installed. Concrete screws come packaged in a kit with the appropriate size drill bit. Drill the pilot hole with an electric drill equipped with the drill bit supplied with the concrete screw kit.