One potential problem when repairing a water shut-off valve leak is that the pressure you put on the packing nut to turn it can cause leaks in other parts of the valve or in the pipe connections.

Tighten the packing nut on the toilet shutoff valve one-eighth turn clockwise to try to seal a leak around the nut. Pro tip: Wrap cloth or masking tape on the plier’s jaws to protect the nut’s finish.