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Check your overflow relief gully (ORG)

If there’s a sewer blockage, your overflow relief gully (ORG) helps redirect sewage safely away from your home and into the garden.

This small outdoor drain is an important part of your home plumbing. Keep it uncovered, working and with a clear drainage path to reduce the risk of costly damage or health hazards.

How does it work?

If there’s a sewer blockage, the overflow relief gully grate is designed to pop off, releasing pressure and directing sewage safely away from your home.

It's the homeowner’s responsibility to make sure the property has a compliant and working overflow relief gully.

If it's not working properly, there's a much higher risk of sewage spilling inside or underneath the home, potentially causing damage and posing a health risk.

Your overflow relief gully should:

  • Be installed at the correct height, which is usually 75mm above the ground and at least 150mm lower than the lowest internal drain (like a shower or floor waste)
  • Have a clear drainage path, so any spills drain away quickly without causing damage
  • Have a fitting (grate) that can pop off completely if there’s a blockage

Your overflow relief gully should not:

  • Be covered by landscaping, garden beds or other objects
  • Be under any building extensions. A plumber should move it as part of a build
  • Be blocked or buried in concrete (e.g. after driveway or paving works)
  • Have a grate that is rusted, filled with silt or stuck in place. It must be able to pop off freely

Do all homes have an overflow relief gully?

Yes, most properties have an overflow relief gully.

We strongly recommend every home has a compliant overflow relief gully as part of its sanitary drainage system.

If it's not possible to install one, a reflux valve may be used instead.

Is my overflow relief gully covered by regulation?

Plumbing regulations under the Plumbing Code of Australia (PCA) and AS/NZS 3500 Plumbing and Drainage apply to all overflow relief gully installations.

If you already have one, a licensed plumber can make a compliance assessment.

If you don’t, contact a licensed plumber for an installation.

Contact us

If you have questions, get in touch:

  • Call us on 1300 657 000 (Monday to Friday, 8am – 5pm)
  • Use Live Chat during business hours