Building a deck over or beside a Sydney Water pipe

Why Sydney Water asks first

Building, digging and even landscaping can harm Sydney Water’s pipes or block its way to them, which is why it checks and signs off building plans ahead of any work. Its October 2025 technical guidelines, Building over and adjacent to pipe assets, list decks alongside swimming pools, carports, non-habitable sheds, fences, retaining walls, driveways and landscaping as “building works”.

The reason is access. Section 2.1 of the guidelines explains that Sydney Water needs to reach its pipes safely at any hour of the day or night, so it can deal with an incident straight away, and that it should never have to take down, shift or change a structure to get to them. The same section sets out the consequence: anything built over or beside its assets without approval will be removed, at the owner’s cost.

Approval also connects to council. Sydney Water says that if your building work needs a development application, the council won’t consent unless Sydney Water has approved your building plans.

The order of the steps

1. Find the pipe on paper

   A service location diagram tells you that a Sydney Water pipe is there, but the guidelines (section 1.7) warn it won’t give you the pipe’s exact position on the ground. You can buy one through Sydney Water Tap in, or get one through Before You Dig Australia (BYDA). Sydney Water says its plans are free from BYDA.

2. Ask the council about consent

   Your council can tell you whether the work needs development consent. Where it does, Sydney Water’s approval of the plans has to come first, before any work begins.

3. Lodge the plans at Sydney Water Tap in

   The online form asks about the project and has you mark where the deck will sit on the block. Where nothing of Sydney Water’s is affected, approval is immediate: an approval letter arrives by email, and the current building plan approval fee is charged.

4. If there is an impact, a coordinator steps in

   Where the plans do affect its pipes, Sydney Water sends you to a water servicing coordinator: a provider on its list who deals with Sydney Water for you. The coordinator is paid by you, and Sydney Water suggests comparing a few. Their job covers going through the plans with you, setting out how the pipes must be protected, and overseeing any concrete encasement or piering that is required.

5. Some plans go to Sydney Water itself

   Coordinators can approve most plans themselves, but some must go up to Sydney Water for a detailed review: work affecting a sewer wider than 300 mm, a pressure sewer, a water or recycled water pipe, Sydney Water land or an easement, or a block within 10 metres of a Sydney Water stormwater asset. The same applies if you plan to dig a basement, build over or next to a Sydney Water asset, or pump water out of the ground (dewatering). You pay for that review, and for a straightforward one Sydney Water generally issues its conditions within 42 days.

6. Take the approval to your certifier

   The approved plans then go to whoever is approving the build, the council or a certifier.

The lightweight structure sheet

Diagram 6 of the technical guidelines covers “lightweight structures over reticulation sewers”, and it is the diagram written for structures like decks, which it names. Its figures, as the guidelines give them:

What counts

Something nobody lives or trades in, that can be taken away easily, covering no more than 36 m². Decks are named, along with carports, verandahs, sheds and pergolas.

Which sewer

Only small reticulation sewers, 300 mm across or less.

Footing beside the pipe

At least 600 mm clear of the side of the pipe.

Footing over the pipe

Can sit right above the pipe, but only with more than 750 mm between the underside of the footing and the top of the pipe.

Near a maintenance structure

At least 600 mm clear of the wall of any sewer maintenance structure.

Load

The design load at footing level must not exceed 50 kPa.

Never underneath

No maintenance structure or sewer fitting may end up beneath the deck, and that includes the point where the property connects to the sewer (requirement 4).

Never enclosed

The deck can’t later be closed in permanently (requirement 9).

The ground

Leave the ground level, and the cover level of any sewer maintenance structure or other surface fitting, as they are unless Sydney Water agrees to a change (requirements 6 and 7).

Machinery

Only light machinery on site, and none driven across the pipe where it has less than 450 mm of soil over it (requirement 8).

The diagram also requires the pipe to sit in a soil trench and be in good condition (inspect it if in doubt), and says other requirements may apply in rock, poor ground or mine subsidence areas. If the diagram’s intent isn’t clear, the guidelines suggest getting technical advice or asking Sydney Water.

What can’t be built over at all

Section 1.5.1 of the guidelines rules out three kinds of asset entirely. Nothing may be built over a pipe that runs under pressure, whether it carries drinking water, sewage or stormwater (vacuum sewers included). Nothing may be built over a sewer maintenance structure or the point where a property connects to the sewer. And nothing may be built over a gravity sewer wider than 750 mm, or over other critical assets such as tunnels.

Building permanent structures over or next to sewers larger than 750 mm is not allowed under the guideline; for those pipes Sydney Water asks to be contacted early, warns it may impose substantial restrictions, and says a specialist engineering assessment would be needed.

Room to work around a maintenance hole

A deck that stops short of a maintenance hole still has to leave room around it. Under section 2.1.2 of the guidelines, a maintenance hole needs a clear working area reaching at least 1 m out from the edge of its cover and at least 2.4 m of clear height above; a maintenance shaft or chamber can make do with 600 mm. The way in matters too: a clear path no narrower than 1 m with 2.4 m of height, and a spot for a maintenance vehicle to park within 50 m.

Getting to a pipe through a foyer, a living space or up a staircase doesn’t meet Sydney Water’s idea of safe, open access (section 2.1.1).