The water that comes out from washing is called the Grey Water. Grey Water Treatment and Recycling Systems are an important for green building methods and practices. The commercial and residential buildings owners have attracted towards the recycling grey water for the savings in energy and potential ecological benefits.

Classification of Household wastewater:
  • Black water: Wastewater from the toilet and garbage disposal.
  • Grey water: All other household wastewater from the bathroom showers, kitchen sink and clothes wash areas and other taps water.

Greywater for irrigation and domestic grey water systems
Decontaminated greywater is used for irrigation. A domestic greywater treatment system diminishes bacteria, chemical pollutants and solids. The Treatment processes includes:
  • Filtering
  • Settlement of solids
  • Flotation and separation of lighter solids
  • An aerobic or aerobic digestion
  • Chemical or UV disinfection
It is a must that the grey water tanks needs to be further treated otherwise health hazards are major problems to the nature

Grey water for toilet flushing
Grey water for toilet flushing and irrigation are being treated by the commercially manufactured systems.
  • The systems consist of multi-chamber tanks which decrease solids by settlement, filtering and floating
  • The water is treated by chlorination or UV and is pumped to the toilet cisterns. The toilet cisterns should have an alternative clean water supply which can be turned on while maintenance is carried out on the Grey Water Treatment System

Commercial Grey Water Treatment Processes:
  • Grey water is separately composed in an underground tank. A screen of 10 mm opening is provided at the inlet of the tank to remove the large suspended particles / debris from the waste stream
  • Aeration is given to confirm that septic conditions do not occur. The grey water is then pumped to the aeration tank by using a submersible pump with cutter mechanism. This will reduce big sized particles to less than 2mm size
  • In the aeration tank, chlorine is added to confirm that the chemical treatment of the wastewater. The aerated effluent is treated using a Pressure Sand Filter to eliminate finer suspended solids prior to reuse
  • Chlorination is applied in the final collection tank for final polishing
To some extent, each Grey Water System will be different, depending on the local policies and application.

  • Reduces demand on drinking water which helps protect water resources
  • Cost saving benefits
  • Available all yearround
  • If the residential households use grey water for any needs, it will be less clean drinking water consumption