Inflow & Infiltration

 “I&I” is a short acronym for a huge problem most sewer communities face, Inflow and Infiltration. Inflow occurs when rainwater is misdirected into the sanitary sewer system instead of storm sewers. Examples are: roof leaders, footer drains, sump pumps, manhole covers, and cross connections from storm drains. The remedy for inflow is to remove improper connections to the sanitary sewer system.

Infiltration occurs when ground water seeps into the sanitary sewer system through cracks or leaks in sewer pipes. The cracks or leaks may be caused by age related deterioration, loose joints, damage or root infiltration. The remedy for infiltration is repairing or replacing the leaking infrastructure. Ignored I&I results in excessive flows in the sewers and into the wastewater treatment plant. This becomes a very costly problem for all of us. I&I affects the quantity of wastewater that needs to be treated, the capacity of your community’s sewer pipes, wastewater treatment plant and ultimately, the rates that we pay to operate and maintain them.

The worst impact of I&I is the likelihood that the sewage can overflow out of the sewer pipe and into our environment. This yucky, gross runoff of untreated sewage, contaminated with fecal matter, urine, and toilet paper, is often referred to as SSO (Sanitary Sewer Overflow). I&I takes up valuable capacity in the wastewater treatment plant and may limit future sewer connections. I&I adversely affects the nutrient loadings for the plant discharge. If ignored, I&I can cost your community many millions of dollars.

You, as a homeowner, can reduce I&I from your property.

  • Check that gutters and outside drains are not connected to sanitary sewers.
  • Avoid planting trees and shrubs over building sewers. The roots can damage the structure of the sewer pipe and cause leaks.
  • Keep caps on your cleanouts. Lawn mowers have a tendency to break the plastic caps. Replacement lids are available at your local hardware store.
  • Ensure that basement drains and sump pumps are not connected to the sanitary sewer.
  • Replace any known broken, leaky or problem sections of sewer pipe that are located on your property.

The Hamilton Township Municipality is responsible for maintaining the sewers and laterals on streets and public right of ways and easements.  The Authority has an on-going program to reduce the quantity of I&I in the sanitary sewer system.  A pothole in the street is easy for all of us to see and know that repairs are needed. Since the sewers are underground, special equipment, technology and techniques are used to locate problems.  Specialized robotic video cameras are lowered into manholes and travel down the sewer pipes.  Flow meters, smoke testing, and other technologies are also used in our program to locate problems in sewers.  As problems are located, the approach to repair and rehabilitation and/or replacement projects are evaluated, prioritized and planned.  Continued investigations and repairs of sewers will persist for many years into the future.