Inflow & Infiltration

The terms "inflow" and "infiltration" both refer to clear water getting into sanitary sewer pipes. Inflow is clear water, generally rainwater, that enters the sanitary sewer pipe through direct connections, such as roof leaders, sump pumps, or foundation drains. Salem maintains a separate storm sewer system, which is intended to carry flow from clear water sources. Infiltration is groundwater or rain water that seeps into the joints of pipes, or through cracks in deteriorated pipes and manholes. A small amount of infiltration is expected in any sanitary sewer system. However, the goal is to eliminate large amounts of I and I into the sanitary sewer system.

Stormwater Information

During rainfall events, I and I takes up capacity in sanitary sewer pipes. It can contribute to backups and cause sanitary sewer overflows, which have the potential to contaminate our land and water. The City of Salem currently has a Consent Order due to sanitary sewer overflows.

Even if it never causes a backup, I and I can be costly to the community. I and I can impact existing system capacity, reducing available capacity for new development and requiring larger, more expensive system infrastructure. Rain water that enters the sanitary sewer must also be treated at the Roanoke Regional Water Pollution Control Plant, increasing the overall cost of treatment. Not only must the water be treated, but the plant itself must also have a reserve capacity to handle the larger flows that will occur during rain events.

Salem is committed to reducing I and I through all available resources. What is the Salem Water Department Doing?

 A broken cleanout cap allows a direct inflow of rainwater and leaves into the sanitary sewer system.

Make sure your roof drains, sump pumps, and other stormwater inlets are NOT connected to the sanitary sewer system. Consider routing them to a planted area of your yard.

Rainwater can also be harvested to use for outdoor watering. Here are instructions for the construction of a safe and cost-effective rain barrel. Storing rainwater helps reduce Inflow and Infiltration by reducing direct inflow into the sanitary sewer system. It also reduces ground saturation during heavy runoff events, which also reduces the amount of water available to seep into your basement. Rain barrels give you a free source of water for lawns and gardens during dry weather, which will reduce your overall water bill. They also help prevent soil erosion and related pollution from getting into our streams.

Replace loose, broken, or missing cleanout caps. Cleanout caps are the first line of defense against inflow and debris that can cause sewer backups. A well-fitted cap also prevents the cleanout from becoming a trip hazard.

Check your pipes for roots. Once roots enter a sewer pipe, they thrive on nutrient-rich water. As roots grow, they widen the cracks in the pipe, as well as create blockages. Never plant a tree or woody shrub near a sanitary sewer pipe or storm drain.

If you see or suspect a sanitary sewer problem, email the City of Salem Water Department, call 540-375-3029, or use the Report a Problem form.