Inflow & Infiltration

Wastewater or sewer systems are designed to carry wastewater from homes and businesses to the Water Reclamation Facility. When storm and/or ground water enters the system through inflow and infiltration (I&I), the sanitary sewer system can become overloaded, which causes sewer backups or overflows, and causes clean water to be mixed with unclean water. Water that enters the sanitary sewer system must be treated, so reducing I&I also means the city is reducing the amount of water that is treated.

How to Reduce I&I

Typical sources of I&I include cracked pipes, improper sewer connections, sump pumps, downspouts, and foundation drains that have been directly connected to the sanitary sewer system.

Any drains that collect storm water (sump pumps, sump basins, outdoor stairwell drains, driveway drains, gutter downspouts, etc.) should drain onto the ground whenever possible, at least 3 feet from the foundation. These types of drains should never be connected to the sanitary sewer system and are illegal.

Many resources are available on the internet which teach about Inflow & Infiltration. A few YouTube videos can be very helpful as well, such as those provided by CRDVictoria about Protecting Our Sanitary Sewer System.

I&I Video: Protecting Our Sanitary Sewer System Part 1

I&I Video: Protecting Our Sanitary Sewer System Part 2

I&I Video: Protecting Our Sanitary Sewer System Part 3

I&I Video: Protecting Our Sanitary Sewer System Part 4

Definitions

• Inflow: Inflow is storm or ground water that enters into the sanitary sewer system through direct connections or major defects. Common sources of inflow are sump pumps, foundation drains, downspouts, and uncapped clean-outs that are directly connected to the sanitary sewer system.
• Infiltration: Infiltration is storm or ground water that seeps into the sanitary sewer system through cracks, offset joints, or defects in pipes and/or manholes.
• I&I: Inflow and infiltration is commonly referred together as I&I.
• Private Sewer Lateral: A private sewer lateral is a sewer pipe that connects a building's internal sewer plumbing to the public sanitary sewer system. The sewer lateral is part of the private plumbing system and is maintained by the property owner.
• Sanitary Sewer: The sanitary sewer is a system of pipes and devices that are designed to carry sanitary sewer, or wastewater, from approved drains in homes and businesses such as sinks, toilets, and showers, to a wastewater treatment plant.
• Storm Sewer: The storm sewer is a system of pipes and channels designed to carry storm and ground water from streets, parking lots, roofs, driveways, sidewalks, etc., directly to drainage creeks, rivers, and/or detention basins.