What is an Overflow Relief Gully?

An overflow relief gully (ORG) is a crucial component of the sewerage system in Australian homes, designed to protect properties from sewage backups and overflows. Typically located outside near bathrooms or laundry areas, an ORG is a drain-like fitting made of plastic or metal with a removable grate on top.

The primary purpose of an ORG is to prevent wastewater from backing up into living areas in case of a sewer blockage. Here’s how it works:

1. The ORG is installed at the lowest point in the sewerage system, about 150mm below the lowest connected drain in the home.
2. If a blockage occurs in the sewer line, causing water levels to rise, the ORG’s grate is designed to pop off.
3. This allows excess sewage to overflow outside the home rather than inside, protecting the interior from damage and health hazards.

• Typically made of plastic or metal alloy
• Usually 100-150mm in diameter
• Located outside the home, often near bathrooms or laundry areas

• Existing disconnector gullies or vents can be converted to ORGs
• Must be lower than all other wastewater fixtures in the home

• Overflow ground vent
• Reflux valve with shaft and approved type cover at surface level

In Australia, ORGs have been part of plumbing standards since the mid-1970s. The installation must comply with specific regulations:

• Must be at least 150mm lower than the lowest fixture in the house (e.g., shower, toilet)
• Should be at least 75mm above the surrounding ground to prevent stormwater ingress

• Size and design must accommodate potential sewage overflow volume
• Typically 100-150mm in diameter to handle expected flow rates

• Surrounding area should slope away from the house to direct overflow
• A geotechnical investigation may be necessary for proper installation

• Must be easily accessible for maintenance and inspection
• Should not be covered by landscaping, garden beds, or objects

• Should have a loose-fitting grate that can pop off easily in case of overflow
• Some older models may require manual twisting, which is not ideal

• Must comply with local plumbing codes and regulations
• In Australia, installation is regulated by the National Plumbing Code AS35007

By considering these factors, plumbers and homeowners can ensure that ORGs are properly designed and installed to effectively protect properties from sewage backups while complying with local regulations.

Several signs indicate your overflow relief gully (ORG) needs maintenance:

• Slow-draining water: If you notice water draining slowly from sinks or other fixtures, it could be a sign of a drain blockage in your ORG.
• Water pooling in the ORG: If water accumulates in the ORG, it indicates a blockage or improper functioning.
• Sewage smell: A persistent or noticeable sewage odour around your property may indicate that your ORG is dry and not maintaining its water seal.
• Damaged or missing grate: A broken, corroded, or missing grate on your ORG requires immediate attention to ensure proper functioning.
• Visible obstructions: If your ORG is covered by landscaping, garden beds, pot plants, or other objects, it must be cleared to function correctly.
• Incorrect installation level: If your ORG is not at least 150mm lower than the lowest fixture in your home and 75mm above ground level, it may need adjustment.
• Regular overflow issues: If your ORG is frequently overflowing, it indicates a problem with your home’s plumbing system that needs to be addressed.
• Cracked or damaged ORG: Visible cracks or damage to the ORG structure can compromise its effectiveness in diverting overflow.
• Difficulty in grate removal: If the grate doesn’t pop off easily or requires manual twisting, it may not function correctly during an emergency.
• Stormwater ingress: If you notice stormwater entering the ORG from nearby downpipes or sloping ground, it needs to be addressed to prevent sewer system overload.

Homeowners are responsible for ensuring their property has a properly functioning ORG. To maintain an effective ORG:

• Keep the area around the ORG clear of obstructions like landscaping, garden beds, or pot plants.
• Regularly check that the grate can easily pop off.
• Ensure there’s a clear drainage path for quick overflow drainage.

By maintaining a well-functioning ORG, homeowners can significantly reduce the risk of sewer spills inside their homes, preventing costly damage and potential health risks associated with sewage overflows.

To properly clean your overflow relief gully (ORG), follow these steps:

1. Remove any visible debris or obstructions from the grate and surrounding area.
2. Pour nearly boiling water mixed with white vinegar down the gully to help dissolve and flush away any buildup.
3. Use a plunger to create pressure and dislodge any stubborn blockages
4. For tougher clogs, try a mixture of baking soda and vinegar. Pour half a cup of each down the drain, cover it, let it sit for an hour, then flush with hot water
5. If the blockage persists, use a plumbing snake or auger to remove deeper obstructions physically
6. For hard surfaces around the ORG, wash them thoroughly with clean water and a chemical disinfectant.
7. Ensure the grate can pop off easily by checking its mechanism.
8. Regularly inspect the area around the ORG to keep it clear of landscaping, garden beds, or other objects that might interfere with its function.

Remember, if these methods don’t work or if you’re unsure about the process, it’s best to contact a licensed plumber for professional assistance.

Installing an overflow relief gully (ORG) yourself is not recommended. You should hire a licensed plumber to install or modify an ORG for several reasons:

1. Regulatory compliance: The installation of ORGs is regulated by the National Plumbing Code AS3500 in Australia. A licensed plumber will ensure the installation meets all legal requirements.
2. Correct installation: Proper ORG installation is crucial for its effectiveness. It must be at least 150mm lower than the lowest fixture in your house and 75mm above ground level. A professional plumber has the expertise to ensure correct placement.
3. Plumbing system knowledge: ORGs are part of a complex plumbing system. A licensed plumber understands how the ORG integrates with your home’s entire sewerage network.
4. Safety concerns: Incorrect installation can lead to sewage backups in your home, posing serious health risks.
5. Property protection: A properly installed ORG protects your home from costly damage due to sewage overflows.
6. Specialised tools and skills: Professional plumbers have the necessary tools and expertise to install ORGs correctly, including making any required alterations to existing plumbing.

Given these factors, contacting a licensed plumber at North East Plumbing for ORG installation or modifications is best to ensure it functions correctly and complies with local regulations.