Most backyards in South East Queensland have a sewer main running through them, usually near the back or side boundary, exactly where people want a patio. It rarely stops a build, but it does decide where the posts can go.
The basic clearances
Anything built within 3 m of a sewer or council stormwater main is checked against the Queensland Development Code, MP1.4. The standard answer, which a certifier can approve on their own:
- Footings at least 1.2 m from a sewer main up to 225 mm, or a stormwater pipe up to 375 mm.
- At least 1.5 m from the centre of a manhole.
- 1 m clear all round the property connection point, with 2.4 m of clear height above it.
- The pipe sits at least 300 mm above the footing’s zone of influence, so the post load does not press on it.
- Bigger mains (sewer over 225 mm, stormwater over 375 mm) need 3 m, and anything closer always goes to the pipe owner.
Manholes: never build over them
A manhole (maintenance hole) has to stay open and reachable, because the pipe owner needs to get a truck and equipment to it. You cannot build over one, and most authorities want clear space around it:
- QDC, Logan and Redlands: 1.5 m from the centre of the manhole.
- Urban Utilities (Brisbane, Ipswich, Scenic Rim): 1 m clear around every maintenance cover and the property connection.
- Gold Coast: 1 m clear and 2.4 m of open height above the cover.
- Never raise the ground over a manhole lid or pave it in. Lids must stay at ground level and visible.
Footing type matters
Urban Utilities, for example, accepts bored piers 1 m from a small sewer but excavated pad footings only 0.6 m away when taken deep enough, and driven piles must stay 5 m away. Pressure water mains cannot be built over at all. The engineer picks the footing to suit.
Who owns the pipe
- Logan: Logan Water, run by council. A design that misses the clearances goes to council as a build-over (BOONRI) referral.
- Brisbane, Ipswich and the Scenic Rim: Urban Utilities owns the sewer and water mains. In Brisbane, stormwater belongs to council, so a job can involve both.
- Redlands: Redland City Council is its own water and sewer provider.
- Gold Coast: the City of Gold Coast. Footings within 1.5 m of a sewer must be bored or screw piers, and anything inside a council easement needs the City’s consent.
The Redlands lightweight exception
Redland City Council allows a lightweight Colorbond patio, deck or carport on a slab with no footings to run up to 10 m over a sewer, as long as it keeps clear of manholes and connection points. It is one of the more generous rules around.
How we handle it
We locate the sewer from the property plans before we quote, and set the posts out to miss it where we can. When a post has to go close, we get the engineering and lodge the build-over application with the right authority. It adds a little time, but it is routine.