Waste water undergoes primary, secondary and tertiary treatment before it is reused for any alternative purposes. The black water and the grey water are both basic classification of waste water. The determining factors in treating will be the facilities available and the quantity of waste that is targeted to be taken off the waste water. This requires different kinds of treatment and purification processes before it can be made designed for any alternative uses.

Waste water can be broadly classified into grey water and black water. It signifies the water that comes from clean sources and that which does not contain human wastes or any other potentially harmful substances that pollutes the environment. It has mostly that comes from dish washing or laundry cleaning.

Black water while the name signifies contains human waste and can not be reused without proper processing. When water is been through different quantities of processing it ensures reduction of contaminants and also ensures cleaner. There are 3 effective treatment methods and before these purification processes, waste water undergoes a pretreatment process. This method helps in removing larger wastes that's chances to clog the pumps and cause delay in the primary treatment.

Primary treatment is a procedure where heavy solids which are contained in the water to settle into different layers of removable waste. This treatment ensures heavy wastes getting settled in underneath and mobile water treatment system oil, greases and other lighter waste materials floating at the top.

Secondary water treatment is just a specialized process that helps in removing the microbial unicellular life or the large amounts of microbes. This method also involves the utilization of filter beds that helps in the oxidation and purification of water.