What Does Inflow (I/I, DWI, RII, II) Mean?
Inflow refers to the entrance of non-sewage water -- such as storm runoff or snowmelt -- entering a sewer system. Inflow generally occurs during times of precipitation, often through means other than storm drains. Its entry into the sewer system carries biota and chemicals scoured from roads, yards, cellars and roof gutters.
Trenchlesspedia Explains Inflow (I/I, DWI, RII, II)
Inflow increases the cost of sewage treatment and the overall operation costs of
treatment facilities. The overburden caused by the introduction of excessive water resulting from inflow can
cause a sewer system to exceed its design capacity. This means the
treatment facility is incapable of handling the amount of sewage and
gray water presented for treatment. System failure can cause a sewers to back up, resulting in public health concerns and financial losses for municipalities.