Overflow Relief Gully (ORG)

It is the householder’s responsibility to ensure their home is fitted with a properly designed and functioning ORG.

How to manage your ORG

In the event of a sewer blockage, your ORG plays an important role in keeping potential sewage overflows outside and away from the interior of your home.

Ensure your ORG is kept clean and clear, allowing the grate to pop off completely in the event  of a sewer blockage.

What does it look like?

An ORG is a drain-like fitting located outside your home. The shape and size of ORGs can vary.

Generally, ORGs are between 100 and 150 mm in diameter and are made of plastic or metal alloy.
In some properties, there are fittings that might look like an ORG called disconnector gullies or vents. These can be converted to an ORG provided they are lower than all other wastewater fixtures in the home.

Illustration of an Overflow relief gully

Are ORGs covered by regulation?

The National Plumbing Code AS3500 1998 regulates the installation of ORGs.

How does it work?

An ORG works because it is fitted at a depth lower than all other waste water fixtures in the home, particularly the shower base and toilet (where an internal sewer overflow is most likely to occur if an ORG is not installed).

In the event of a sewer blockage, the ORG grate should pop off to release pressure and confine the overflow to the outside of your home. The home interior is protected from the overflow.

The ORG should be installed so it sits at least 150 mm lower than the lowest fixture in the house. For example, your shower or toilet. It also needs to be least 75 mm above the ground to prevent stormwater flowing into your ORG.

Why aren’t all homes fitted with an ORG?

Most properties constructed after 1976 have an ORG surrounded by concrete, near an external wall.

Buildings connected to the sewer prior to 1976 may not have an ORG unless additional work has been undertaken after this time.

Over the years, many styles of ORG have been installed, all of which met performance standards at the time of installation.

Who should I contact to install an ORG?

The best ORG is one that is unhindered, where the grate pops off completely in the event of a sewer blockage.

Your ORG should not be:

  • covered by landscaping or garden beds
  • covered by an object, such as a pot plant
  • unable to pop off because it has corroded, been concreted or filled in with dirt
  • a model that needs to be manually twisted in order to pop off.

A licenced plumber should be contacted if you do not have an ORG or require an alteration to an older fitting.