Phyto-purification is an extensive solution which takes up the space (more space than a compact filter, but less space than a sand filter) of between 2 and 4m²/population equivalent (PE). The filters are sized by the accommodation capacity of the 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.