Sullage (grey water) which is mentioned above, if collected in a storage TANK separately can be treated by AERATING it to prevent it from turning septic, and then DOSED with a coagulant, chlorinated and then subjected to filtration by pressure sand filtration followed by activated carbon filtration and stored in a separate overhead tank or tanks from which it can be used for flushing TOILETS and other uses where fresh or potable water is not required.

However, the current practice is to combine sullage and sewage (black water) and treat the mixture in an STP (Sewage treatment plant). This practice has come in predominantly to reduce the cost of construction of two separate plants and because space is now at a premium in any BUILDING.

Sullage (grey water) which is mentioned above, if collected in a storage tank separately can be treated by aerating it to prevent it from turning septic, and then dosed with a coagulant, chlorinated and then subjected to filtration by pressure sand filtration followed by activated carbon filtration and stored in a separate overhead tank or tanks from which it can be used for flushing toilets and other uses where fresh or potable water is not required.

However, the current practice is to combine sullage and sewage (black water) and treat the mixture in an STP (Sewage treatment plant). This practice has come in predominantly to reduce the cost of construction of two separate plants and because space is now at a premium in any building.