Phyto-purification is an extensive solution which takes up between 2 and 4m²/population equivalent (PE) -- more space than a compact filter, but less space than a sand filter. The filters are sized by the accommodation capacity of the related housing, not by the number of inhabitants, with one main room = 1 PE. For example, a house with 3 bedrooms, 1 kitchen-dining room, and 1 living room has 5 main rooms. The sanitation system must then have a capacity of 5 PE. Individual sanitation, being means-based and not end-based, would require at minimum 10m² of planted filters.