How much water do they drink per day? I have several in a pond bog natural filtration system and they seem to each consume 5-10 gallons per day. Could be the reason my pond is losing 100+ gal of water twice a day?
Yes, several Elephant Ear plants could cause a noticeable water loss.
They are fast growers and have a large root system that craves water. If you pond is not large, it would be best to plant in soil near the pond.