Private Property Infiltration & Inflow

In 2013, the City of Ashland implemented a Private Property Infiltration and Inflow (I/I) Program to help reduce I/I and improve operations of the sanitary sewer system. This program was initiated because of basement backups and sanitary sewer overflows resulting from the excess stormwater, snowmelt, and groundwater entering the sanitary sewer system during wet weather periods.

Infiltration & Inflow Definition

“Clear water (from storm water, snow melt, and groundwater) that enters the sanitary sewer system is collectively referred to as infiltration and inflow (I/I). In general, infiltration is clear water that enters through cracks, breaks, and other defects in the sanitary sewer system; inflow is clear water that enters through direct connections to the sanitary sewer system, such as sump pumps and storm sewer pipes.“


The City has taken significant steps to help reduce I/I and better manage excess flows. A large project was completed in 2008 that helped to reroute flows, significantly reducing the frequency of sanitary sewer overflows along the lake shore. In 2009, a City-wide study was completed to identify and prioritize the areas of the City contributing the largest amounts of I/I. 

In 2011, nearly 8 miles of sewer was televised, and 231 manholes were inspected in Sewer Districts 7 and 8, the two districts with the greatest amount of I/I. In 2013, nearly $550,000 of grant money was used to rehabilitate and replace 3,830 linear feet of public sewer and 72 manholes in the two districts, significantly reducing I/I. The City will continue with the methodical reduction of I/I on the publicly-owned portions of the sewer system. However, focusing only on public side of the problem will not reduce I/I to acceptable levels.


I/I reduction in the privately-owned portions of the sewer system will be pivotal to the overall success of the I/I removal program. As part of the City’s efforts to identify and reduce sources of I/I originating from private property, private property inspections will be completed by City staff. During a half-hour appointment, City staff will be looking for connections to the sanitary sewer system such as sump pumps, area drains, foundation drains, and downspouts. 

Current plans include a multi-year inspection program, starting in the sewer districts with the greatest amount of I/I. Homeowners will be notified by mail when inspections are being completed in their district.

If you were referred here by the mail notice, please use the Time Trade website to schedule your appointment or call Public Works at 715-682-7061.

Related Documents