Your Overflow Relief Gully: What It Does and Why It Matters
The small grate outside your laundry protects your home from sewage. Here is how to keep it working.
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What it is
The overflow relief gully is a small grated outlet in the ground outside your house, usually near the laundry, kitchen or bathroom. It is connected to the sewer line, and its loose grate is designed to lift if the drain blocks downstream, letting sewage escape outside rather than coming up through a floor waste or toilet inside.
Why it matters
If the gully is buried, covered by pavers, or set higher than your floor wastes, sewage has nowhere to go but into the house. Fixing that problem before a blockage happens can save a very unpleasant clean-up.
Correct height
The top of the grate should be at least 150 mm below the lowest floor waste inside, and at least 75 mm above the surrounding ground so stormwater cannot run into it. Many gullies in Ferntree Gully have been buried by garden beds, mulch and paving over the years.
Warning signs
Water or sewage around the gully grate, a bad smell near it, or a grate that has lifted are all signs of a blockage in the sewer. Stop using water and call 03 7036 4101.
What we can do
We can raise a buried gully, replace a missing or broken grate, and clear the blockage that caused it to overflow. We also check the drain with a camera to find out why it blocked.
Ferntree Gully ground and pipes
Ferntree Gully's ground changes as you climb towards the ranges: clay and silty loam on the lower streets, rockier, steeper ground near Upper Ferntree Gully and The Basin. Most homes built before the 1980s were connected with earthenware sewer pipe, and on a slope every joint moves a little over the years and lets roots in. Water service lines from the meter are often long and run through rocky ground or under established gardens. Stormwater has to be carried down the block and away from the house. We use cameras, locators and pressure tests to see what is happening before we dig.
Related services
- Emergency plumbing
- Blocked drains
- Hot water
- Gas fitting
- Hot water replacement
- Heat pumps
- Leaking taps
- Burst pipes
- Toilets
- Leak detection
- Pipe relining
- Stormwater
- Roof and gutters
- Bathrooms
- Kitchens and laundries
- Backflow and maintenance
More guides
Questions on this topic
Who is responsible for blocked gully?
On your property, the gully and the drain leading to it are generally the owner's responsibility. If the blockage is in the water corporation's sewer main, they look after it. A camera inspection shows where the problem is.
Can I cover my overflow gully with pavers?
No. The grate must stay visible and free to lift, or sewage may overflow inside the house instead.
Why foothills homes call us
Foothills know-how
Sloping blocks, big gums, clay sewers and gas heaters from the 1970s: this is the plumbing we work on every day.
Price first, work second
A licensed plumber finds the fault and agrees a fixed price with you before anything starts.
Camera, not guesswork
Drain cameras, pressure gauges and leak detection tools show the real cause before we dig or replace.
Respect for your home
Boot covers, drop sheets, old parts taken away and the job tested with you.
Get a free quote
Tell us what is going on and a licensed Ferntree Gully plumber will call you back.
How quoting works
Ring 03 7036 4101 or send the form with a short note, and a photo if you have one. A licensed plumber calls you back, asks a few questions and books a time. On site they find the cause, explain your options and give you a fixed price. Nothing starts until you agree, and larger jobs get a free written quote.
Need a plumber in Ferntree Gully?
Ferntree Gully, Upper Ferntree Gully, Boronia, Rowville, Knoxfield and the Knox foothills. Quote-only: the plumber finds the fault, then gives you a fixed price.