For ultimate safety low-voltage AC is the answer. The New Rena OEM Low Voltage water pump w/transformer can replace many pumps with a 3-wire heavy cord. It can be used in both fountains and aquariums and is UL approved for indoor and covered patio use.
It is an ideal replacement for pumps with those bulky 3 wire grounded cords that are difficult to manage in a small tabletop fountain and also works great in smaller desktop aquariums and fountains. Recommended for use with clean water, the pump has a convenient side-mounted sliding switch for flow control.