Natural water filter for rooftop rain water
About 15 years ago I read about a way to purify water without special filters or chemicals. It was a system that took water and ran it through a 10' or 15' planter with a variety of plants. The combination of plants, soil and gravel worked to purify so that water that went in one end of the planter was purified by the time it came out the other end.
If I remember correctly the system was designed by Japanese naturalist and was being used in high rise offices.
There was also a system that used a variety of plants, fish and waterfalls to purify water for a natural swimming pool. I remember that the landscape architect that was using this system commented that his mother did not like swimming in a pool where the fish were nibbling on her toes.
I'm looking for something like this to purify rooftop rain water to use the water for a small fish pond.
Any in0put would be appreciated.