To make water suitable for drinking a high technological process is needed. Strangely enough the end product is carelessly handled. Much is flushed through the toilet or given to plants. Naturally we can waste less by using water-saving sanitation however real improvement will be realised by recycling water. Shower water can be used as 'grey' water to for example flush the toilets. Rain water and surface water can be used to do the laundry. 'Black' water can be locally purified and the mineral rich water can be used for the garden.
Water can be cleaned locally by using reed
Systems are required for this. Sometimes invisible but sometimes also as a part of the architecture. For example, ditches, canals and ponds for water storage, with the added advantage that the direct environment can profit from good air humidity, or water tanks for rain storage that at the same time can be used as a heat buffer.
From white to grey to black to grey to white
The naming grey and black water comes from the colour of the water; grey water is water used for showering and washing and has a somewhat grey colour. Waste- water that contains faeces turns black after a short time.
Gärtnerhof in Vienna
In the living complex Gärtnerhof in Vienna, Austria rainwater is used for doing the laundry and the flushing of the toilets. The local precipitation on the 155m2-roof surface per home is enough for 6,6m3 water per month, enough for the laundry and the toilets. In spite of the Austrian rules that forbid the use of rainwater as shower water on hygienic grounds, there are two households that shower with the rainwater at their own risk.
The grey- and black water is purified on the inner area. The system consists of five serially placed basins; a sedimentation basin, three covered with reed and reed-mace cleansing basins and a mountain sediment pond. The purified water is used by a local market garden. The surplus water is sprayed over nearby fields.
The Canadian biologist Todd designed a 'Living Machine' for the non-profit organisation Ocean Arks International in Falmouth, USA. With this autarkic buildings should be able to be realised separate from the public net. Serially placed tanks purify the water and moreover produce CH4, a source of energy with a clean burn. A similar system is being used in Scotland where the grey black water from ca 200 households is purified. For the present the water is drained on the surface.
Hildrud Pötz Pierre Bleuzé: Zichtbaar, tastbaar, zinvol, Rotterdam 1998
Nancy Jack Todd and John Todd: From Eco-Cities to Living Machines, Berkeley CA 1984.
EcoDesign, Vol VI No.3, 1998