Definition - What does Inflow Pipe mean?
An inflow pipe brings in stormwater from various sources into the sanitary sewer system at points of direct connection to the system or discharge into sinks directly connected to the sewer system. Inflow can be contributed from sources such as footing or foundation drains, roof drains or leaders, drains from driveways, sump pumps, and downspouts.
These inflow pipes are usually illegally or improperly connected to the sewer system. This causes water from sources other than sanitary fixtures and drains to enter the sewer system which should actually be entering the stormwater system or allowed to soak into the ground.
Trenchlesspedia explains Inflow Pipe
Inflow pipes can be illegally and improperly connected by residential homes, and businesses, significantly increasing the amount of water that enters the sewer system. Inflow adds clear water to the sanitary flow and increases the load on the system. This load must then be transported to the waste treatment plant and treated like a sanitary waste. In dry weather, the impact of the inflow can be from minimal to a significant portion of sewer pipe flow.
In wet weather when rainwater runoff starts entering the sewer system along with the water from the inflow pipes, it can fill the sewer system to capacity causing overload. This sewer system overload causes the water to flow at a much higher level than normal, and sanitary fixtures and drains that are below this overload level will experience backflow. The backflow can cause flooding of basements and houses and can even force manhole covers to pop open and spill wastewater onto the streets.