On site sewage management

New Septic tank being installed

What is an On-Site Sewage Management (OSSM) system?

An OSSM is part of the plumbing system on an unsewered property, and normally includes a tank for treating raw sewage and a disposal system. Types of OSSM systems include:

  • septic tanks
  • aerated wastewater treatment systems (AWTS)
  • greywater treatment systems
  • wet and dry composting toilets
  • alternative systems 

These systems include sewage management facilities that treat domestic sewage from up to 10 persons with an average daily flow of less than 2000 litres.


Self-audit checklist

There may be an issue with the system if any of the following are occurring.

  • Water inside the house don’t drain away freely
  • There is excessive noise coming from the system
  • There is a sewage odour coming from the system or disposal area
  • There is pooling of liquid around the system or disposal area
  • The system is not protected from stormwater run-off
  • There is excessive or a large amount of vegetation around the system and/or disposal area
  • For AWTS systems, they have not been serviced regularly (quarterly) or maintained.

If using subsurface disposal 

  • Cattle/horses are allowed in the disposal area
  • There is visible damage to the trenches

If using surface irrigation

  • Irrigation sprinklers aren’t working
  • There are missing sprinklers
  • Spray is not contained within a specific area with limited drift or allowed to go over property boundaries
  • Inappropriate hoses and plumbing fittings being used (fittings should be non-domestic, low pressure, low volume)