Sewer Inspection Program

Sanitary Sewer Infiltration and Inflow (I&I) are presumed by most experts to be the primary cause of most sewer backups throughout the country. Backups and overflows occur when rain and ground water enter the sanitary sewer system, especially during storm events. This rain and groundwater overwhelms the design capacity of the sanitary sewer system and creates surcharges which result in sewage discharging into homes, streets, and streams.
 

Sewer Sanitary Inlfow and Infiltration

Sewer Sanitary Inflow and Infiltration
Infiltration occurs when groundwater seeps through damaged sewer laterals, connections between the laterals and the mains, or through cracks or separated joints in the sewers or manholes. While each infiltration source might allow a relatively small amount of water into the sanitary system the impact can be very substantial when multiplied by the thousands of homes connected to the system. Sources of inflow include downspouts, sump pumps, areaway drains or other outdoor drains improperly connected to the sanitary sewer. Inflow sources can be major contributor due to the volume of water associated with each source.

The City has been working to reduce infiltration throughout the public sewer mains and manholes utilizing a variety of methods. However, data indicates that a significant portion of the I&I in a typical sewer system actually occurs on private property. The diagram below demonstrates the common privately owned defects.

Frequently Asked Questions 


Should I have a Sewer Inspection?


Homeowners can benefit from television inspection of their sanitary sewer lateral, as well as a general inspection of their site drainage conditions.  Sewer lateral repairs are often the most expensive emergency repair that a homeowner will face – typically costing more than $10,000.  Contracting for inspection can provide homeowners with an indication of the health of their drainage system and identify proactive measures to protect their home.
 

What is Infiltration and Inflow?


Infiltration and Inflow (I&I) are common engineering terms used to describe how non-sewer water finds its way into a sewer system.  I&I are a frequent cause of sewer backups throughout the country and consume expensive sewer conveyance and treatment capacity.  Infiltration occurs when groundwater seeps through damaged sewer laterals, connections between the laterals and the mains, or through cracks or separated joints in the sewers or manholes. Sources of inflow include downspouts, sump pumps, areaway drains or other outdoor drains improperly connected to the sanitary sewer. 
 

What else is the City doing to prevent I&I?


The City has been working to reduce infiltration throughout the public sewer mains and manholes utilizing a variety of methods, including repairs to manholes, replacing pipes, and lining old pipes with fiberglass.  Unfortunately, a significant portion of the I&I in a typical sewer system occurs on private property.  Privately owned defects include private lateral pipes and direct connections of downspouts, area drains, foundation drains or sump pumps to the sanitary sewer system. 
 

Where can I learn more about the program?


The City’s Department of Public Works oversees the City’s Sanitary Sewer System.  Contact DPW via email at DPW@fallschurchva.gov or by phone at 703-248-5350 (TTY 711).