Smartrek: Inflow and Infiltration
Infiltration can be described as groundwater that enters pipes through openings such as holes, breaks, joint failures, and connection failures. This amount varies with the season and is especially heightened after storm events and extended periods of precipitation. It is most commonly expressed in terms of the total land area served (in gallons per acre per day, GPAD). Pipe length and diameter are also taken into account when measuring infiltration.
Inflow of surface water into the wastewater system is caused by heavy precipitation and includes yard drains, roof drains, footing drains, cross-connections with storm drains and downspouts, and manhole covers with holes. During extreme weather, the storm sewer system may be overly full, causing water to back up and pool.