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Sullage Systems: Greywater Matters

What Is a Sullage System?

A sullage system handles greywater—wastewater from kitchens (via a grease trap), showers, baths, basins, and laundries. It generally includes: 

  • A blackwater septic tank for toilet waste 
  • A grease trap to catch fats and food scraps 
  • A greywater sullage tank with a pump to distribute greywater to the land application area (like irrigation trenches or hoses) 

While sullage systems are no longer approved for new installations in Queensland, existing systems must be well-maintained to avoid health and environmental risks. 

Maintenance Tips for Sullage Systems

  • Desludge the greywater tank and grease trap every 12 months. 
  • Pump out the septic tank every 3–5 years. 
  • Rotate greywater hoses regularly to avoid soggy patches. 
  • Mow and maintain plants around land application areas. 
  • Don’t overload the system with too many users. 
  • Use septic-safe products—avoid bleach and harsh cleaners. 
  • Fix leaks, turn off taps when not in use, and never pour oils down the sink. 

 Don't: 

  • Cover grease traps or plant trees nearby (roots can damage pipes). 
  • Let wastewater overflow onto neighbouring properties—this can pose a serious health hazard. 

Common Problems to Watch For

  • Overflowing trenches or soggy ground 
  • Blocked pipes (from tree roots or fats) 
  • Odours or pest problems 
  • Sludge build-up causing pump failure 
  • Greywater pump submerged in sludge 

Property owners are responsible for keeping their system in safe, working condition. If your sullage system is failing or causing issues, Council may require repairs or replacement. 

Grease Traps

Greywater

Plumbing