Sources of Inflow and Infiltration and How We Find Them

Properly connected sewer system.

Inflow sources within the public right-of-way can include sanitary manhole covers and storm water catchbasins that are inadvertently tied into the sanitary sewer. Private land areas (outside of public right-of-way) inflow sources include roof downspout connections, yard and driveway drains, broken or missing sanitary lateral cleanout caps, and sump pump connections to the sanitary sewer system. These connections are illegal and can add thousands of gallons of storm water into the sanitary sewer system per household during large rain events. Inflow sources are usually easy to remediate.

Private infiltration sources can include broken lateral sewers, faulty lateral connections, tree root penetration, and broken cleanouts.

These sources can overload the sanitary sewer system and cause sanitary sewer backups into homes and businesses, as well as sanitary sewer overflows (SSOs) to nearby creeks.

More Info on Inflow and Infiltration

Smoke Testing

Involves pumping smoke through sewers from manholes in streets and observing where smoke exits. The exiting smoke can indicate a broken pipe or identify where roof or foundation drains are improperly connected to the sewer system.

Camera Inspections

Cameras can be robotically sent down sanitary sewer lines and along each side sewer to record a video of sewer conditions. Inspections can identify breaks, root intrusion, leaking water and deteriorating conditions.

Dye Testing

Involves pouring non-toxic fluorescent colored dye down roof drains or catch basins to see if that dye makes its way into the sewer. This provides verification that the storm drainage being tested is directly connected to the sewer.