How does my septic system work?

Some 25 % of Canadians treat their wastewater with a septic system.

A septic system treats your wastewater on your own property, and releases clean treated water back into the groundwater. A properly functioning septic system receives your household’s wastewater and treats it to a safe level before returning it to the environment.

A conventional septic system is composed of a septic tank and a soil filter, also called a leaching bed, dispersal or drain field. The septic tank separates liquids from solids and helps to breakdown some of the organic matter in wastewater. Partially treated wastewater from the septic tank flows into the dispersal field. The drain field is typically a network of perforated plastic pipes. The dispersal area is a soil filter that uses natural processes to treat wastewater from the septic tank. The septic tank and dispersal field must be professionally installed to ensure correct and safe operation.


How do I know if there is a problem with my septic system?

Warning signs that there may be a problem with your septic system include the following:

  • The ground around your septic tank or drain field is soggy or spongy to walk on
  • There is lush green zones concentrated in areas of your dispersal system
  • Sewage odours are noticeable
  • Gray or black liquids are surfacing in your yard or backing up through the fixtures in your house
  • Nearby low or areas or ditches are showing signs effluent
  • Toilets, showers, and sinks are backing, gurgling, or taking longer than usual to drain
  • Backup of sewage into your house
  • Needing to frequently pump your septic tank
  • A change in plant growth and algae (excessive growth) in nearby ponds and lakes
  • Contamination in well water tests (increased levels of nitrates and coliform bacteria)

Why is my septic system failing?

A properly maintained septic system will last for years. However, there are a number of reasons why a septic system may fail.

  • Lack of Maintenance – Septic systems do require periodic maintenance from a qualified professional. A septic tank should be pumped out every few years when 1/3 of the tank volume is filled with solids.
  • Overloading the System – Your septic system is designed to operate around the daily needs of your household. A sudden, dramatic increase in water usage can overload the system.
  • Contaminating the System – Septic systems rely on bacteria to break down the waste material, and it is therefore important not to poison these microorganisms. Certain materials should never be put down a drain or toilet. Paints, solvents, thinners, and common household chemicals, if put down a drain or toilet, will adversely affect your septic system.