If a toilet leak is coming from the point at which the water supply tube enters the tank, first try tightening the fastening nut, located just under the tank. If that doesn’t work, do the following.
1.
Empty the Tank
Shut off the water, flush the toilet, and sponge out any water remaining in the tank.
2.
Replace the Gasket
Disconnect the water-supply line, remove the fastening nut, and replace the old beveled gasket of the ballcock assembly (on the inside of the tank) and rubber washers with new ones (Fig. 1). Tighten the fastening nut with your fingers. Then holding the ballcock, tighten the nut snugly without overtightening, or you may crack the tank. Apply Teflon tape (on plastic parts) or spread pipe joint compound (on metal parts) around the compression ring and/or female threads of the water-supply line, and tighten carefully.
3.
Replace Tubing, If Needed
If the water-supply tube itself is leaking, replace it with flexible braided tubing.
