Humus toilet and the biological purification plant
Since 1975 Hundertwasser had been preoccupied with the humus toilet and the possibilities of biological water purification, especially the plant purification systems. In all his residences he used humus toilets. He developed various construction plans for the humus toilet and described their function and use. The humus toilet functions in the house, even in living quarters. There is no odor, there are no flies if care is taken to cover the refuse with damp humus. No sewage is needed, no flushing with water, no ventilation duct, no chemicals, not even electricity.
For urine and waste water from the household, Hundertwasser designed a biological water-purification system using aquatic plants and put it into practise in several versions (KunstHausWien). The plant purification system can be used in bright and warm interiors using the following plants: calla, cypress grass, waterhyacinth, papyrus, scouring rush, spiderwort, alocasia, jointed twig-rush, climbing fig etc. Outdoors, bulrushes, reeds, cattails, water mint and water flag, etc., are used.