Greywater
The European Standard 12056-1 defines gray water as faecal-free, low polluted waste water, as obtained for example when showering, bathing or washing your hands, but also comes from the washing machine and can be used for the treatment to domestic or industrial water. The kitchen waste, however, is excluded because of its high exposure to fats and food waste. Grey water can be - for example, through the use of water recycling systems - for a secondary use process. In general, the cleaning is done on a purely mechanical- biological means; more recently, bio- membrane filters are used. The clear water so produced is hygienically clean. It can be used for watering the garden, the house cleaning and flushing toilets; also wash can thus be safely washed (when processed to bathing water quality, as is common in Europe). In a household with 4-5 people, the consumption of about 90 cubic meters of water per year summed. Compared to the weather-dependent use of rainwater recycled process water is always available.
In the U.S., the attempt to re-use of gray water has led to design the irrigation system more sustainable. In Japan and Europe, especially the approach is to use gray water within the household as process water, particularly for flushing toilets, again. In Germany, institutions rely on water recycling facilities, such as the Hamburg Fire Brigade.
Various ways are possible to use water from the budget twice. There is the possibility to create such facilities by specialist firms. However, it can also be purchased commercially available water recycling systems and installed by any installer that are suitable for households. Such systems form by the process of wastewater treatment plant with a sedimentation, aeration, anaerobic purification, sludge deposition. They find their typical applications where the waste water of several families, hotel rooms, etc. is merged and treated together.
Another principle follows an imaginary rather detached system, with the means of "low- tech" is an attempt to achieve maximum water savings with a minimum of storage space, technology, capital and operating costs, with a short service life of the water to be treated. For the buffering of peak consumption is rainwater ( and only in the third instance: drinking water ) was used. The typical per capita water consumption decreases to values below 60 l / day.
According to an economic analysis of the Fachhochschule Wiesbaden can be in Central Europe already gray water systems from a connected user base of about 150-200 people (thus eg in hotels ) operate economically. At high drinking water and wastewater fees quick payback is otherwise likely. Due to the expected increase in the cost of water and wastewater, it is deemed advisable or gray may also invest in a new building or a total renovation of the installation of a residential building in a separate piping system for rainwater harvesting. In areas with greater water scarcity (eg Southern Europe) the gray water recycling will almost always useful.