There is currently no single, explicit, globally recognized definition of grey water. The European Standard 12056-1 defines grey water as wastewater with a low pollution level and no fecal matter such as produced by shower, bath, wash basin and washing machine and which can be used to prepare service water. In contrast, wastewater from the kitchen is not included due to the high levels of fats and food waste it contains.

The use of grey water, like the use of rainwater or well water, is a suitable way of reducing potable water consumed in buildings, helps protect the environment and lower the costs of water consumption. Furthermore, less wastewater is produced as a result of recycling grey water since the water is used twice, which leads to additional ecological and economic potential. It can be safely said that grey water recycling in large groups of buildings and hotels can be a sensible means of saving water and wastewater with little effort and offers significant returns due to its relatively low level of contamination representing an extremely efficient way of cutting costs.

There are various technical approaches to recycle grey water. Technologies differ considerably in their complexity, size, recycling performance and recycling quality. There are direct-use systems, retention systems as well as physical, chemical, biological and bio-mechanical systems.  Comparative studies have shown that the membrane bio-reactor (MBR) currently represents the best technology to recycle grey water thanks to its outstanding cleaning performance. Grey water systems using MBR technology also have the advantage that they require little space and can guarantee the relevant quality parameters even if the inflow characteristics fluctuate, which means that the requirements of the European Directive concerning the quality of bathing water are always guaranteed.

iWater grey water plants work in accordance with leading edge technology using MBR equipment. Our grey water plants are designed to treat grey water from showers, baths and wash basins. Wastewater from kitchens should only be connected with an additional pre-clarification system due to the fats contained in the wastewater. The barrier effects of the immersed cartridges

with ultra-filtration membrane (with a pore size of 0.00005 mm) used in our technology mean that we can guarantee the safe and complete retention of all dirt particles and the complete retention of all bacteria; even the smallest viruses are removed with a retention rate of 99.999 %. This allows the recycled water to be used at all points of consumption where potable water is not required. We recommend using the water for toilet flushing, cleaning purposes, car washing and garden irrigation.