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Private wells and septic systems

Septic systems

How septic systems work

A septic system processes all the wastewater from your house. There are two stages:

  • A double-chambered concrete tank, which has baffles to prevent raw waste from flowing into the second chamber
  • A system of water-permeable pipes called the tile bed. Aeration may also be added between the first and second stages.

Bacteria in the system break down sewage and wastewater. Undigested solids settle in the bottom of the tank as sludge. Lighter solids float to the top as scum. Liquid containing dissolved materials is taken from between these two layers and flows continuously and evenly into the tile bed. As the wastewater works its way from the tiles through the bed it is treated one last time, before being discharged into the water table. At every stage, bacteria are at work, digesting the material. End products of the system still contain nutrients, bacteria and chemicals.

Problems with septic systems

The tank should be pumped out regularly or the sludge/scum can be drawn into the tile bed, eventually overloading the system. After time, this can lead to partially treated wastewater appearing directly on the ground surface. Sewage will contaminate the soil and the water supply, including your well or a neighbour’s.

The same situation can happen if too much water is dumped into the tank. Excess household chemicals, soaps and detergents can also kill the bacterial action in the septic tank and affect its ability to process waste.

More information:

Signs of trouble

  • Grass over the tile bed is unusually green or spongy to walk on
  • Plumbing takes longer to drain
  • You can smell sewage
  • Grey or black liquids surface in yards
  • A test of your or a neighbour's well water shows contamination

Septic system dos

  • Know where the tank is located and keep a maintenance record
  • Make sure you hire a licensed septic tank servicing company for regular inspections and that they take care not to damage the inlet or outlet baffles or tees during pumping
  • Get the tank pumped to remove the accumulated scum and sludge. Pumping intervals should be based on regular inspections (including measurement of scum and sludge levels in your tank).
  • Plant grass over the leaching field; it will help prevent erosion and absorb excess water.
  • Divert surface runoff water from roofs, patios, driveways and other areas away from the leaching field
  • Conserve water to avoid overloading the system

Septic system don’ts

  • Use your toilet as a trash can
  • Use more soap or detergents than you need
  • Install a garbage disposal without checking whether your septic tank can handle the added volume
  • Poison your septic system and the groundwater by pouring harmful chemicals and cleaners such as chlorine bleach, toilet bowl cleaners, borax and drain openers down the drain
  • Drive over or park cars, trucks or heavy equipment on the tile bed
  • Plant trees or shrubbery in or near the tile bed, because the roots will grow into the lines and plug them
  • Pave the tile bed with concrete or asphalt
  • Drain your water softener backwashes into the septic tank. Use a class-2 leaching pit (dry well) or the sump hole in your basement.
  • Add "starters" or "conditioners"; some will interfere with normal operations; others (particularly degreasers) contain cancer-causing substances that could contaminate the groundwater
NEVER flush these items into the septic tank (they cannot be broken down by bacteria or will destroy the bacterial action):
  • Loose hair
  • Cigarette butts
  • Coffee grounds
  • Fat, grease or oil
  • Dental floss
  • Paper towels
  • Disposable diapers
  • Sanitary napkins, tampons or condoms
  • Kitty litter
  • Gauze bandages
NEVER flush chemicals into the septic tank (they could contaminate surface and groundwater):
  • Paints
  • Varnishes
  • Thinners
  • Waste oils
  • Photographic solutions
  • Pesticides or herbicides