SSO & Bypass Public Notification

The City of Waterloo, IA Waste Management Services Department would like to inform city residents that under the Iowa Department of Natural Resources (IADNR) and Environmental Protection Agency (EPA) the city is required to notify the public of a Sanitary Sewer Overflow (SSO) or Bypass event. Listing of SSO & Bypass Public Notification Report Forms is listed at the bottom of this web page.


If you see a “WARNING SEWAGE” sign(s) “KEEP OUT OF WATER” these signs are marking a location(s) where a Sanitary Sewer Overflow (SSO) or Bypassing has happened or is ongoing with sewage or wastewater contaminating the street, ground, lawn, creek, stream, or river. Residents and citizens are asked to stay out of these sanitary sewer overflow areas as long as a sign(s) are posted. All persons, children, and pets should keep out of these sewage overflow areas and waters.

This is a “Warning Sewage” sign that will be posted by a SSO, manhole overflow, or waterway receiving sewage

manholeoverflowIf a resident or citizen sees a manhole that is overflowing onto the street or ground, you can contact Waste Management Services twenty-four hours a day, seven days a week at 291-4553, if no person answers please leave a message.

Pictured is an example of a manhole overflow or SSO. Click here for more examples

Recent SSO and Bypass Events:
  •  July 15, 2024 at 8:38 PM, bypass pumping began at WCF & N and Midland St. An estimated 123,600 gallons was diverted from the sanitary sewer to the storm sewer, to the Cedar River. Pumping occurred intermittently and stopped at 3:50 AM for a total pumping time of 5.15 hours.  A sample was collected, sewage warning sign #27 posted, no barricades or disinfection needed.  
  •  July 9, 2024 at 4:29PM, bypass pumping began at WCF & N and Midland St. An estimated 54,000 gallons was diverted from the sanitary sewer to the storm sewer, to the Cedar River. Pumping stopped at 6:44 PM for a total pumping time of 2.25 hours.  A sample was collected, sewage warning sign #19 posted, no barricades or disinfection needed.   
Listing of SSO & Bypass Public Notification Report Forms

SANITARY SEWER OVERFLOW (SSO): Wastewater that flows out of a sanitary sewer (or lift station) as a result of flows exceeding the hydraulic capacity of the sewer or stoppages in the sewer. SSOs exceeding hydraulic capacity usually occur during periods of heavy precipitation or high levels of runoff from snow melt or other runoff sources. Is an unintentional release of sewage from a collection/sewer system of untreated or partially treated sewage before it reaches the treatment plant.

BYPASS: The intentional diversion of waste streams from any portion of a treatment (or pretreatment) facility.

BYPASSING: Used to describe the diversion of raw or partially treated wastewater to a receiving body of water.

SANITARY SEWER: A pipe or conduit (sewer) intended to carry wastewater or water-borne wastes from homes, businesses, and industries to the POTW.

INFILTRATION/INFLOW (I/I): A combination of infiltration and inflow wastewater volumes in sewer lines, without distinguishing the source.

INFILTRATION: The water entering a sewer system, including building sewers, from the ground, through such means as defective or cracked pipes, pipe joints, connections, or manhole walls. Infiltration does not include, and is distinguished from, inflow.

INFLOW: The water discharged into a sewer system, including service connections, from such sources as roof leaders; cellar, yard, and area drains; foundation drains; cooling water discharges; drains from springs and swampy areas; manhole covers; cross connections from storm sewers, combined sewers, catch basins; storm waters; surface runoff; street wash waters; or drainage. Inflow does not include, and is distinguished from, infiltration.

GREASE AND OIL: a group of substances including fats, waxes, free fatty acids, calcium and magnesium soaps, mineral oils, and certain other nonfatty materials. Water-insoluble organic compounds of plant and animal origins or industrial wastes that can be removed by natural flotation skimming. Fats, Oils, and Grease (FOG).

The following is a list of Frequently Asked Questions for Sanitary Sewer Overflows:
What are Sewer System Overflows?
Sewer System Overflows (SSOs) are discharges of raw sewage from municipal sanitary sewer systems or from privately owned sewer collection systems. SSOs can release untreated sewage out of manholes and onto city streets, playgrounds and into waterways before it can reach a treatment facility. SSOs are often caused by blockages and breaks in the sewer lines, and excess water from I/I.

Why do sewers overflow?
SSOs occasionally occur in almost every sewer system, even though systems are intended to collect and contain all the sewage that flows into them. When SSOs happen frequently, it means something is wrong with the system. Problems that can cause chronic SSOs include:

  • Infiltration and Inflow (I&I): too much rainfall or snowmelt infiltrating through the ground into leaky sanitary sewers not designed to hold rainfall or to drain property, and excess water inflowing through roof drain connection, footing drain connection, sump pump connection to the sanitary sewer, broken pipes, badly connected sewer service lines

  • Undersized Systems: Sewers and pumps are too small to carry sewage from newly developed subdivisions or commercial areas

  • Pipe Failures: broken or cracked pipes; sections of pipe settle or shift so that pipe joints no longer match

  • Pipe Blockage: Sewer pipe plug or blockage from Fats, Oils, and Grease (FOG); tree roots grow into the sewer; debris or rags build up in pipes

  • Equipment Failures: pump failures, power failures

  • Deteriorating Sewer System: improper installation, improper maintenance or lack of preventative maintenance, as sewer flushing/cleaning, on the sanitary sewer system; aging sewer pipes and manhole structures; widespread problems can be expensive to fix and develop over time, communities may have to curtail new development until problems are corrected or system capacity is increased.


What health risks do SSOs present?
Because SSOs contain raw sewage they can carry bacteria, viruses, protozoa (parasitic organisms), helminthes (intestinal worms), and boroughs (inhaled molds and fungi). The diseases they may cause range in severity from mild gastroenteritis (causing stomach cramps and diarrhea) to life-threatening ailments such as cholera, dysentery, infections hepatitis, and severe gastroenteritis. People can be exposed through:

  • Sewage in drinking water sources.

  • Direct contact in areas of high public access such as basements, lawns or streets, or bodies of water as lakes, creeks, and rivers used for recreation.


What other damage can SSOs do?
SSOs also damage property and the environment. When basements flood, the damaged area must be cleaned and disinfected to reduce the risk of disease. Cleanup can be expensive for homeowners and municipalities. Rugs, curtains, flooring, wallboard panels, and upholstered furniture usually must be replaced. A key concern with SSOs that enter oceans, estuaries, rivers, lakes, streams, or creeks is their effect on water quality. When bodies of water cannot be used for drinking water, fishing, or recreation as swimming and water-skiing, society experiences an economic loss. Fishing and shellfish harvesting may be restricted or halted.

How can SSOs be reduced or eliminated?
Many avoidable SSOs are caused by inadequate or negligent operation or maintenance, washing pans and plates in the sink that contain grease or cooking oil, inadequate sewer system capacity, and improper sewer system design and construction. These SSOs can be reduced or eliminated by:

  • Regular sanitary sewer system inspection, cleaning/jetting, and maintenance can eliminate many of these problems and keep the system functioning smoothly.

  • Reducing infiltration and inflow (I/I) through system rehabilitation and repairing broken or leaking service lines, removing footing/foundation drain connections and sump pump connections to the sanitary sewer.

  • Enlarging or upgrading sewer, pump station, or sewage treatment plant capacity and/or reliability.

  • Construction wet weather storage and treatment facilities to treat excess flows.

  • Communities also should address SSOs during sewer system master planning and facilities planning, or while extending the sewer system into previously unsewered areas.

  • Not washing pans or plates that have grease or cooking oil, sometimes called FOG, on them down the sink or drain, but to wipe cooled grease from pans or plates with a paper towel or pour cooled cooking oil into a can and dispose of grease and cooking oils in the garbage.

  • A few SSOs may be unavoidable. Unavoidable SSOs include those occurring from unpreventable vandalism, some types of blockages, extreme rainstorms, and acts of nature such as earthquakes or floods.


Questions may be directed to the Waste Management Services’ office,
3500 Easton Avenue, Monday - Friday, 7:00 a.m. – 4:00 p.m.,
or by calling 291-4553 during office hours.

Listing of SSO & Bypass Public Notification Report Forms