Biological purification of water to any degree up to drinking water

An installation and a method for water purification which includes sequentially: A first section where the waters enter the installation and where the incoming waters come into contact with living microscopical and macroscopical organisms in order to achieve the removal from the waters, as sludge, water contents in suspension, whether such contents existed in the incoming waters or whether such contents were produced after the incoming waters entered the works and they came in contact with living organisms. A second section comprising a series of structures like structure which are connected so that each one drains its water into a following one, while each structure of the type of structure contains a layer of inert material into which grow suitable plants which utilize for their growth contents within the incoming waters so that such contents are removed from the flowing waters. The total area of the series of structures like structure is determined from the desired degree of purity of the outgoing waters, for a particular quality of incoming water.