Sanitary sewage includes liquid wastes of domestic and industrial places.
Storm sewage includes surface runoff developed during and immediately after the rainfall over the concerned area.
Dry Weather Flow(D.W.F)
The sanitary sewage which flows in dry season is known as dry weather flow.
It consists of two types of sewage:
a) Domestic sewage.
b) Industrial sewage.
The quantity of D.W.F depends upon the factors:
a) Infiltration & ex-filtration.
b) Nature of industries.
d) Rate of water supply.
Wet Weather Flow(W.W.F)
The combined flow of sanitary sewage and stormwater in the rainy season is known as wet weather flow.
Variation In Flow Of Sewage
The flow of sewage is directly related to the flow of water supply. As the water supply varies from hour to hour, day to day, month to month and season to season. The flow of sewage also varies accordingly. The peak flow should be ascertained by different observations.