What is an Overflow Relief Gully?

how to fix smelly drains

Today dad and I installed an overflow relief gully (ORG) to a house that had one installed in the wrong place. What is an Overflow Relief  Gully? It’s a drain like fitting with a grate on top and has a bend bottom. It is installed 150mm lower than the lowest drain point in the house. The house we fixed their ORG with had it installed higher than the floor grate inside which meant when the council sewer backed up, instead of the sewerage overflowing out of the ORG, it came up through the floor waste in the ground floor bathroom. This is the deepest opening to the sewer main and it was unfortunately inside the house! It’s not the nicest site to wake up to on an early Saturday morning.

An ORG is to be installed at the deepest part of the sewer drain OUTSIDE so that if the the sewer line backs up or blocks, the effluent will spill out of the ORG outside rather than through the deepest opening inside the house to avoid damage. It’s a by-law and council requirement that all houses and new dwellings have one to avoid this problem. It would pay to ensure that if your house doesn’t have one that you call you local licensed plumber to install one.

The plumber will require a copy of the drainage plan to your house and if you are unable to give him or her one, you are able to purchase one from your local council. It can be a relatively easy job to install providing the main sewer line into the house isn’t plumbed straight through the house. In our case today, the sewer line ran alongside the house and we were able to locate it via the drainage plan and install the ORG.

Unfortunately some new houses have been built without an ORG and the only way a plumber has gotten away with not installing one is not getting the water and drainage certified by the local council. If the house has been inspected by council, you can be assured that an ORG has been installed onto your property.

To maintain an ORG, ensure that the trap bottom has a water seal to stop sewer smells and ensure that you don’t cover up the ORG or else, you will cause the sewerage to flow elsewhere… quite possibly into your house.