Common Problems, Fact Sheets and Check Lists

Common problems identified with on-site sewage management systems include:

  • Too much wastewater going into the system which causes effluent to flow too quickly through the septic tank before bacteria have a chance to work.  Solids can be pushed through the system, clogging absorption trenches;
  • Too much sludge and scum in the tank. Not having a tank de-sludged regularly will result in the tank failing and untreated effluent with heaving solids flowing out of the tank in the absorption trench; and
  • Toxic chemicals going into the system like solvents, oils, paints, disinfectant, pesticides, household cleaning products and bleaches that kill the helpful bacteria in the septic system.  This stops the digestion of effluent and pollution of the absorption trenches.

Signs of a failing on-site sewage management system

Signs of failing on-site sewage management system include:

  • Water not draining away easily from basins and sinks in the house;
  • Drain pipes making a gurgling noise;
  • Sewage smells from the drains or system;
  • Water backing up into sinks or yard gully; and
  • Wastewater pooling over the disposal area.

Preventing Problems


  • Learn how your sewage system works and its operational and maintenance requirements;
  • Learn the location and layout of your septic system and land application area;
  • Have your septic tank de-sludged every 3-5 years to prevent sludge build-up, which may clog pipes and transpiration beds/trenches;
  • Conserve water! Conserving water around the house will reduce the amount of wastewater needing to be treated.  This will result in less frequent de-sludging and longer life of your system;
  • Check household products for suitability for use in septic systems; and
  • Engage a contractor to regularly check and service your system;
  • Keep a record of servicing’s, inspections and other maintenance.


  • Put large quantities of bleaches, disinfectants, whiteners, nappy soakers and spot removers into your septic system – they kills off the helpful bacteria that digest the waste;
  • Allow any foreign materials such as nappies, tampons, condoms and other hygiene products to enter the system – they cause blockages and expensive servicing and repairs;
  • Use more than the recommended amounts of detergents;
  • Put fats and oils down the drain – they clog the system;
  • Install or use ‘sinkerators’ – instead dispose or compost of your fruit and vegetable scraps separately; and
  • Let children or pets play on the land application area where they could be exposed to harmful bacteria.

Factsheets and Checklists