Sewage

Preventing sewage overflows on your property

Overflow Relief Gully

An overflow relief gully (ORG) is a small drain located outside of the home, usually connected to the end of the house sewer. It is designed to release any odours or sewage overflows outside of the property in the event of a blockage and is a critical part of the sewerage system.

It is the property owner’s responsibility to make sure their home is fitted with a properly designed and functioning ORG. Most homes constructed after 1976 will have at least one ORG　and property owners should ensure that their ORG is not covered by garden beds, landscaping, plant pots and bins or blocked by soil or debris.

The grate on the top of the ORG should be loose so that it can pop off and release any sewage spills in an emergency.　 If the grate is covered or buried, it will not function properly and sewage will be released within the home instead.

Property owners are encouraged to located their ORG and check that they are not obstructed. Installation of ORG is regulated under the National Plumbing Code and they must only be installed by a licensed plumber. It is important to ensure that the ORG is installed below the level of the lowest plumbing fixture in the home and above the ground level outside to prevent inflow of storm water. If property owners are unable to locate an ORG on their property, they should contact a licensed plumber to either try and locate the existing one or to install a new one.

ORG can vary in appearance; the picture shows the standard modern ORG design. Generally they are 100mm to 150mm in diameter with a plastic or metal alloy grate and a concrete surround. They are installed close to the external walls of the home.

It is important to ensure the grate on your ORG is loose so that if it gets clogged or blocked, the pressure will lift it off and the gully will overflow outside.

The image below shows the ORG at ground level and the grass　clippings across the top indicate that rainwater drains into it. The ORG is not designed for this.

Rainwater channelled into the sewer overloads the system and increases the likelihood of the sewer backing up. When a new home is built the ORG is installed at the correct height for its plumbing certificate. However, when landscaping is done, the ORG’s function as a sewer overflow can be compromised because the surrounding earth is made　level with it or even sloped to drain into it.

Residents should ensure ORGs are raised above the surrounding area and undertake rectification work if required.

Stormwater

Stormwater is water collected or discharged as a result of rain and its run-off.

Collection areas include:

• Roof water
• Surface water (run-off from paved and unpaved areas)
• Sub-soil water (water accumulated within the ground).

Stormwater should NEVER be directed into the sewerage system. It can overload the system making treatment plants unable to cope which can lead to overflows (sometimes in people’s houses).

Directing water into the sewage system is illegal under the Water Supply (Safety and Reliability) Act 2008.