Sanitary Sewer Overflows




Table of Contents
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  1. Learn about the sanitary sewer system and what you can do to help prevent sewage spills
  2. More information on sewer spills
  3. Ten terms to help you better understand your sewer system
  4. What is the difference between "sanitary sewers" and "storm drains"?
  5. Why are sewage spills a public health, environmental and economic problem?
  6. What are the main causes of sewage spills?
  7. Keeping fats, oils and grease out of the sewer system
  8. How should we properly dispose of grease and oils?
  9. Keeping rubbish out of the sewer system
  10. Keeping rainwater and other excess water out of the sewer system
  11. What is infiltration and inflow?
  12. Why are infiltration and inflow big problems?
  13. Who is responsible for the infiltration and inflow problem?
  14. What can you do to prevent and reduce infiltration and inflow?
  15. What should you do if you see a sewage spill?
  16. Where can I obtain more information?

Preventing Sewage Spills
Caution SignOverflows and spills from sewer lines onto our roadways and into our streams and oceans spoil our beautiful Hawaiian environment and can endanger public health. Sewage spills are costly to clean up (increasing your sewer bills) and can even hurt our tourist industry by causing beach closures. In a typical year, there are over 400 spills statewide involving more than two million gallons of raw sewage!

Learn about the sanitary sewer system and what you can do to help prevent SEWAGE SPILLS!

A Quick Overview
Preventing sewage spills is quite simple. Spills are simply caused by clogged pipes and/or too much flow. All everyone needs to do is keep unwanted things out of our sewer pipes such as grease, trash, rainwater and tree roots.

Illustrated below are some of the causes of sewage spills and how you can help prevent these spills (click here to download a higher resolution image shown below):

Causes of Sewage Spills

More Information on Sewage Spills
Now that you have a feel for the basic ways to prevent sewage spills, take some time to learn about the fascinating details of sewage spills and your underground sewer system. By reading through the information presented below, you can learn:

  • Important sewer system terms.
  • The difference between "sanitary sewers" and storm drains.
  • Why sewage spills are a BIG problem.
  • Typical causes of sewage spills.
  • How to keep grease and oils out of the sewer system.
  • How to keep rubbish out of the sewer system.
  • What infiltration and inflow are and why it is important to keep rainwater and other excess water out of the sewer system.
  • What you should do if you see a sewage spill.
  • Where more information on your sewer system can be obtained.

Ten Terms to Help You Better Understand Your Sewer System

  1. "SEWAGE" or "WASTEWATER." This is the "used" water that contains human wastes from toilets and water from other sources such as sinks, showers, washing machines, etc. In addition to being odorous, sewage can contain large amounts of germs that cause disease. The term "wastewater" is often used in place of "sewage" to make things sound more pleasant when discussing this unpleasant subject.
  2. "SANITARY SEWER SYSTEM," also known as "WASTEWATER COLLECTION SYSTEM," or "SEWERS." These are pipes through which sewage is carried from homes and businesses to a treatment plant. The sanitary sewer system includes the main sewer lines in the streets and the branch lines to individual sewer customers called "sewer laterals."

    Sewer systems are generally designed to flow by gravity through sloped pipes until it reaches either the treatment plant or a sewage pumping station (which pumps the sewage up to another higher sewer or a treatment plant).

    Although sewage is very unsanitary, the term "sanitary sewer" is used because the sewer pipes are separate from the pipes used for storm water drainage. This helps protect public health and the environment. In some older cities, sewage and rainwater flow through the same pipes. This can cause major environmental and public health problems because untreated or partially treated-sewage is discharged into streams, rivers and other water bodies during heavy rain.

  3. "SEWER LATERAL." This is the sewer pipe that connects a building's plumbing system to the main sewer line in the street. Maintenance of sewer lateral pipes located within private property is generally the responsibility of the property owner. Sewer laterals are also called "service laterals," "house laterals," or simply "laterals."
  4. Sewer Cleanout"SEWER CLEANOUT." This is a pipe rising from the sewer lateral to the ground surface with a removable cap or plug. It is used to access the sewer lateral to free blockages. A sewer cleanout is usually located just inside the property line. There may be additional sewer cleanouts at various other locations in your property.
  5. "WASTEWATER TREATMENT PLANT" or "WASTEWATER RECLAMATION FACILITY". These are facilities where organic matter, bacteria, viruses and solids are removed from sewage through physical, biological and chemical processes. The treated wastewater (called effluent) may be disposed of by discharging it to water bodies (mainly the ocean in Hawaii), injecting it into the ground, or reusing it for irrigation or other beneficial non-potable (non-drinking) uses.
  6. Infiltration"INFILTRATION." This refers to groundwater (water found below the ground surface) that enters sewer pipes through cracks, pipe joints, and other system leaks. Because sewers in coastal areas are typically buried deep, they are often located below the water table. Since most sewer lines do not flow full (under pressure), groundwater "infiltrating" into the sewer line is actually more of a problem than sewage leaking out of the line. Storm events can raise groundwater levels and increase infiltration of groundwater into sewer pipes. The highest infiltration flows are observed during or right after heavy rain. Too much infiltration will overload the sewers and cause spills!
  7. "INFLOW." This is rainwater that enters the sewer system from sources such as yard and patio drains, roof gutter downspouts, uncapped cleanouts, pond or pool overflow drains, footing drains, cross-connections with storm drains, and even holes in manhole covers. Inflow is greatest during heavy rainfall and like infiltration, can cause excessive flows and sewage spills.
  8. "PATHOGENS." These are harmful germs in raw sewage that cause diseases such as cholera, dysentery, hepatitis and gastroenteritis.
  9. Manhole Cover"MANHOLES." Sewer manholes are underground structures used to provide access to underground sewer lines and are usually found in a street, parking area or sidewalk. Access is required to periodically inspect and clean the lines. Sewer manholes typically have heavy round covers with the words "Sanitary Sewer" on the cover.
  10. Sanitary Sewer Overflow"SANITARY SEWER OVERFLOW." Sewage spills are technically called "sanitary sewer overflows" since it involves the overflow of sewage from the sanitary sewer system. The word "sanitary" is used only because the overflow is from the sanitary sewer system, and not because the raw sewage is sanitary! (See definition of sanitary sewer above). For simplicity, we will use the term "sewage spill" or "sewage overflow."

    Sewage overflows often occur from sewer manholes in the streets. Sewage can also backup into homes through your toilets, showers and floor drains. Sewage spills are caused by sewage filling the sewer pipes behind the clog to the point where it spills out of an opening in the system (generally the lowest manhole, shower drain or other plumbing fixture).