How to build over a sewer pipe

Quick summary

• Building over a sewer pipe in QLD requires approval from your local council and must comply with the Queensland Development Code MP 1.4 to ensure the sewer’s functionality, safety, and maintenance aren’t compromised. 
• Sewage pipes are surrounded by a Zone of Influence, which must be considered during construction. Clearance distances range from 3m for certain buildings to 10m for ground anchors, with rules applying to structures within or near these zones. 
• To apply for approval, you’ll need to submit detailed site plans, structural designs, and any engineering reports to authorities like Unity Water or Urban Utilities.

Sewer pipes are one of those things that we tend not to think about before it's too late, like we’ve begun building on top of them and accidentally burst one in the process. Not only is this extremely unfortunate and puts a spanner in your building works timeline, but it can also leave you with hefty expenses and fines. But what are the rules when it comes to building over or near sewer infrastructure? Let’s take a deep dive into how to build over a sewer pipe.

Various councils have different rules regarding building over a sewer pipe. It’s vital that you check with your local council every time you build. All our information is specific to South-East Queensland.

Can you build on top of a sewer pipe?

Yes, you can build over a sewer pipe, but there are some crucial factors to consider before moving forward. Any construction over a sewer pipe will need to adhere to the Queensland Development Code (QDC) MP 1.4, or you might need specific approval through a comprehensive application process. 

The main considerations for approval include: 

• The main building work must not adversely affect the functionality of the sewer pipes on your property. 
• The weight of the structure mustn’t damage the sewer pipe or create pressure on it.
• The building must not interfere with the ability to maintain the sewer infrastructure. 
• Safety must be a priority, ensuring that there is no risk of harm to those living on the property, builders carrying out the works, or maintenance workers required to maintain the pipes. 

With the rise of smart infrastructure in QLD, councils might now incorporate new technologies such as real-time monitoring systems to detect stress on the pipes. This might lead to more precise design requirements for building over sewers, making the entire process quicker and less demanding of council approval. 

To build over a sewer, you’ll need to gain council approval. You’ll also likely need a structural engineer to help you create a design that will meet all the necessary requirements outlined in the code.

It might even be worth consulting with your local utility provider, as there might be new technology-driven solutions that can impact clearance or load-bearing restrictions. For example, flexible pipe protection and underground utilities mapping could be viable options to protect your sewer pipes while you’re building on your property.

What is the Zone of Influence?

When it comes to sewer pipes, there is what is known as a sewer zone of influence. Imagine if you drew lines at a 45-degree angle from the bottom of the sewer in each direction until they reach the ground surface. The area you’d have within these boundaries is the sewer zone of influence. The purpose of this is to determine what parts of the land are most likely to affect the sewer line.

With advancements in ground-penetrating radar (GPR) and drone technology for infrastructure inspections, it’s possible that the zone of influence could be better mapped and understood to avoid preventable accidents damaging your pipes. Some councils might make adjustments to your specific zone based on new soil analysis or real-time data on the condition of the pipes. However, it’s important that you check with your local authority to see if this is something they’re exploring yet.

Who are Unity Water and Urban Utilities?

Unity Water and Urban Utilities are statutory authorities run by their respective local governments. They provide similar water supply and sewerage services, but in different areas.

Urban Utilities is an independent board, but its shareholders are the Brisbane, Scenic Rim, Ipswich, Lockyer Valley and Somerset councils. They’ve recently implemented a smart grid for wastewater management, which might affect how building proposals are assessed in high-density areas in the future. 

Unity Water is owned by the Moreton Bay Regional Council and the Sunshine Coast Council and services these two areas. It has recently upgraded some of its infrastructure to incorporate advanced monitoring sensors in its sewerage and water systems. This might make the approval process easier and quicker in some areas. 

Depending on where you live, either Urban Utilities or Unity Water is responsible for the sewer lines leading to your property. Property owners are responsible for the pipes within their own infrastructure.

In Logan, Redland and the Gold Coast, water services are provided by the respective local councils.

What are the rules for building over sewer pipes?

Rules for building over sewer pipes protect both your building and the pipe itself. If not properly thought out, the weight of your building could damage the pipes, which in turn could lead to some very unpleasant substances leaking onto your property.

When building over a sewer, water main, stormwater drain, or combined sanitary drain, the proposed building work must be assessed and meet Queensland Development Code specifications. To read the rules, click here for the official document. This outlines the acceptable solutions and performance requirements you need to meet.

Below is a general outline of where the rules specified in the ODC apply and where they don’t. If in doubt, it’s best to speak to your relevant service provider and double-check.

Where the rules apply

When planning on building over sewer pipes, the rules outlined in MP 1.4 apply to properties:

• They contain relevant sewer infrastructure or are adjacent to a lot that does.
• Those are adjacent to a road reserve that contains relevant infrastructure.
• Those are under a registered service provider’s easement.

Where the rules do not apply

You do not need to comply with the building rules if your building is more than the following minimum distance from the sewer infrastructure:

• 3 metres away for a Class 1 (houses or dwellings of a domestic or residential nature) or Class 10 (non-inhabitable buildings and structures including sheds, carports, fences and swimming pools) building
• 5 metres away from a Class 2-9* building
• 5 metres away for driven piles and piers
• 1o metres away for ground anchors and rock bolts

The rules also won’t apply to any internal alterations, repairs or changes to an existing structure or building so long as they don’t

* Class 2-9 buildings include boarding houses, apartment buildings, office buildings and more. Click here for more information.

How to get building work approval

To build over a sewer line, sewer mains or any sewerage infrastructure, you’ll need to apply with a building application to the relevant service provider.

Unity Water

Unity water requires contacting a qualified building certifier for any building work that is on or next to a property with water or sewer infrastructure or easement on it. If your work cannot meet the standards set out in the Queensland development code MP 1.4, you’ll need to make an application.

When applying, you’ll need the following:

• Site plans which show all existing and proposed buildings and structures, water and sewerage infrastructure and the property connections to said infrastructure.
• A statement that illustrates which of the acceptable solutions you can’t meet and how your alternate solution still meets the related performance within the code.
• Elevation views of your proposed building work.
• Design drawings by a structural engineer that show the footings and foundations of your proposed building work and how they relate to the sewerage infrastructure.

While Unity Water will consider requests to approve building work that encroaches on an easement protecting their infrastructure, they rarely grant them.

Urban utilities

Like Unity water, Urban utilities don’t accept self-assessment referrals, so you’ll need to contact a building certifier.

You’ll likely have to supply the same documentation as outlined for Unity Water.

Are my plans eligible for approval?

With various types of plans needing assessment, it’s difficult to know whether yours are eligible without hearing the specifics. For alternative solutions, an assessment manager will need to determine whether your proposal is feasible. Buildi will help you determine your new build’s chances of getting approval. We’ll also let you know if you may need to make adjustments to make your building plans as easy, safe, and enjoyable as possible. 

Relevant pages

• Using Brisbane flood maps
• Contour surveys explained
• Building on a sloping block
• Storm‑water drainage plans
• CCTV pipe inspections
• Building over easements
• Power‑line setback rules
• Boundary setback rules
• Building near existing trees
• Tree clearing approvals
• Extra rules on rural land