Toilet Flange, Toilet Flanges, Fix Toilet leak at base, Fix Leaky Toilet, Toilet Leaking , Install Toilet A toilet flange is a device located between the base of a toilet and the floor. A wax ring serves as the water seal between the toilet and sewer piping and is placed on top of the flange. Two bolts are attached to the flange anchoring the toilet. Toilets leaking at the base are the # 1 service repairs encountered by plumbing companies. Twist-n-set toilet flanges, shown here, are used to replace damaged toilet flanges and can be used on both PVC and cast iron pipe. The flange is placed inside the pipe and tightened until the gasket expands and wedges tightly between the pipe and the flange.