I've been raising Daphnia magna cultures over the last few months as feedstock for freshwater aquarium fish. From my reading, Daphnia feeds on bacteria and single-celled algae, as well as other small crud suspended in the water column.
Practically, yeast or soy flour can be suspended in water and poured into a tank containing a population of Daphnia, and the critters usually clear the water in a few days. The clarity of the resulting water is quite impressive. Which leads me to...
My question: How effective are these types of organisms at removing harmful bacteria and substances from a volume of water? Lets say you only needed a few gallons of clean water each day, could you have a tap that drew from a tank containing a dense culture of Daphnia, and use that water as drinking water?
I've not found information that studies the quantities of bacteria in the water column before and after introduction of Daphnia or other filter feeders.
P.S. I thought about posting this question in the Sustainability SE but figured I'd get more accurate information here.