How to Install a Basement Toilet That Is Already Rough Plumbed

Insert the flange collar into the soil pipe in the floor to check for fit. Measure any gap between the flange and the floor, remove the collar from the soil pipe and trim off the excess with a hacksaw.

Place the flange’s collar back in the soil pipe. Mark on the ground the locations of the flange’s screw holes. Remove the flange and drill pilot holes in the floor. Replace the flange and drive screws through the holes in the flange and into the floor, so the flange cannot move in any direction.

Slide the closet bolts into the slots on the flange and insert washers over each of the closet bolts. Place a wax ring onto the top of the flange, with the rounded side of the ring pointing upward.

Lower the toilet over the flange so the closet bolts come through the holes in the toilet’s base. Push down on the bowl portion of the toilet until the toilet’s base touches the floor. Slide washers over the closet bolts. Tighten the nuts onto the closet bolts, stopping once the toilet does not move in any direction.

Cut the tops of the closet bolts using a close-quarters hacksaw so three threads appear above the nuts. Thread the end of the water supply line with the plastic nut to the bottom of the toilet’s tank by hand. Tighten the connection with slip-joint pliers. Thread the other end of the supply line to the water supply valve and tighten the connection with adjustable pliers.

Turn the water supply valve’s handle counterclockwise until the handle stops. Wait until the toilet tank finishes filling and flush the toilet once to check for leaks.