DIAGNOSIS A cracked or misaligned water reservoir, or a failed internal hose connection. Leak from the bottom means water is escaping the closed system before it reaches the showerhead.
FIX Unplug the machine. Pull the reservoir out. Inspect the clear plastic tank, especially around the bottom seam and the spout that inserts into the machine. Look for hairline cracks. Also, check the black silicone gasket seated in the machine where the reservoir connects. Make sure it's clean and properly seated in its groove.
IF THAT DIDN'T WORK The leak is internal. The most common failure point is the silicone tubing that connects the pump to the heating tube. This requires disassembly. For most owners, this means the unit is not economically repairable.
HEADS UP Water and electricity are inside that base. If you see water leaking, stop using the appliance immediately. Do not plug it back in until it's completely dry inside, which may take days.