Sydney Water Building Over Sewer Approval NSW 2026: Complete Guide to BOAA, Clearances, Fees & Timelines

If your development site in Sydney has a sewer main running through it — or even near it — you need Sydney Water's approval before construction can legally start. This approval runs in parallel to your DA or CDC, not inside it, and skipping it can result in fines, forced demolition of non-compliant structures, and costly project delays. In this guide, we walk through the entire Build Over or Adjacent to Assets (BOAA) process, clearance requirements, fee structures, and real-world timelines so you can plan your project with confidence.

What Is the Sydney Water Building Over Sewer Approval?

The Sydney Water Building Over Sewer approval — formally known as the Build Over or Adjacent to Assets (BOAA) assessment — is an independent technical review process that determines whether your proposed structure can safely coexist with Sydney Water's underground pipe assets. It sits entirely outside your Development Application (DA) or Complying Development Certificate (CDC) pathway, meaning your council or certifier will not assess Sydney Water compliance on your behalf.

Under the Sydney Water Act 1994, Section 44 gives Sydney Water the authority to halt works on any site where construction has commenced without the necessary approvals. The process is designed to protect critical infrastructure — sewer mains, water mains, and stormwater pipes — from damage caused by building loads, excavation, and construction plant movement. It also ensures Sydney Water can maintain unobstructed access to its assets for future repairs and inspections.

For developers and homeowners in Sydney, this means you must submit your building plans directly to Sydney Water through their Tap In portal, not through the NSW Planning Portal. The outcome is a formal letter of acceptance or refusal with conditions that your builder must comply with during construction. At giantA, we coordinate this process as part of our standard development workflow, running the BOAA assessment in parallel with the DA pathway to minimise delays.

When Do You Need Sydney Water Approval?

You need Sydney Water approval whenever your proposed building, excavation, or landscaping works are near any Sydney Water pipe, drain, or meter. This includes everything from concreting a driveway to constructing a multi-unit residential development. The requirement applies to all property types — residential, commercial, industrial — and to all parties, including local councils and utility companies working on community projects.

Coordinators must refer building plans to Sydney Water directly if the proposed works affect any of the following:

Wastewater pipes larger than 300mm in diameter, pressure wastewater pipes (rising mains), water or recycled water pipes, any property containing a Sydney Water easement, or any property with Sydney Water stormwater infrastructure within 10 metres of the boundary. Additionally, any proposal involving basement excavation near an asset, or dewatering activities, must be referred for specialist engineering review.

Build Over vs Build Adjacent: What's the Difference?

Sydney Water separates its requirements into two categories based on how close your structure is to the asset. Understanding which category applies to your site shapes every design decision that follows, from footing systems to structural engineering specifications.

Minimum Clearance Distances for Building Over or Near Sewers

Sydney Water applies minimum clearance distances based on pipe diameter, depth, and asset type. These thresholds apply before any engineering or protective measures enter the picture. If your proposed footing falls inside these clearance zones, you must either relocate the structure or redesign the footing system before Sydney Water will consider your application.

Additional clearance requirements apply to maintenance structures. You cannot build over any wastewater maintenance structure (manhole, inspection shaft, or access chamber). Sydney Water requires an unobstructed passageway with a minimum width of 1 metre and a minimum clear headroom of 2.4 metres around each structure, and a maintenance vehicle must be able to park within 50 metres. Footings must maintain a minimum 600mm clearance from the wall of any sewer maintenance structure, with design loading at footing level not exceeding 50kPa.

Outright Refusal: When You Cannot Build Over a Sewer

Some situations result in an outright refusal regardless of what engineering measures you propose. If your asset search reveals any of the following within your intended building footprint, your design must change before you proceed with documentation or structural engineering:

Sydney Water will not approve building directly over rising mains (pressure sewers), trunk sewers above 375mm diameter, or any asset listed as requiring open maintenance access. You also cannot build over wastewater property connection points, junctions, or fittings. In these cases, the solution is to relocate the building footprint to achieve the required clearances, or to negotiate an asset adjustment through your Water Servicing Coordinator — though asset relocation is costly and time-consuming.

The BOAA Process: Step-by-Step

The Sydney Water building over sewer approval process has eight distinct steps, each building directly on the last. Starting the asset enquiry early and running the BOAA assessment in parallel with your DA or CDC pathway is the single most effective way to avoid delays.

Step 1 — Obtain a service location diagram. Search your property on Sydney Water's online portal, enter your lot and deposited plan number, and enable the wastewater layers. Note any assets within approximately 10 metres of your proposed building footprint. This costs $22.68 through Tap In (2026–27 financial year).

Step 2 — Submit a Building Plan Approval application. Lodge your plans through Sydney Water Tap In. Sydney Water will ask questions about your project and ask you to place your structure on the property. They use this to determine if your works might affect or limit access to their assets. The BPA application fee is $24.15 (2026–27).

Step 3 — Receive initial assessment. If there's no impact on assets, you're approved right away and receive an approval letter by email. If there is an impact, you're referred to a Water Servicing Coordinator (WSC) for detailed assessment. The WSC is a Sydney Water listed provider who acts on your behalf — you pay them market rates for their services.

Step 4 — Specialist Engineering Assessment (if required). For assets over 300mm diameter, pressure pipes, or complex scenarios, the WSC refers your application to Sydney Water as an 'out of scope' application. This requires a Specialist Engineering Assessment (SEA) report prepared by engineers meeting Sydney Water's Engineering Competency Standard. Some submissions require independent verification.

Step 5 — Footing and structural design. Your structural engineer must set footing depths so no part sits within the clearance zone. This often means switching from a standard strip footing to a pier-and-beam or piled system that transfers loads past the sewer main. Provide your engineer with surveyed pipe centreline coordinates, invert depth, and pipe diameter.

Step 6 — Asset protection measures. Where required, concrete encasement of the pipe or a bridging slab distributes load away from the pipe barrel. Your engineer must confirm the proposed mix strength and reinforcement layout meet Sydney Water's minimum encasement dimensions in their design report.

Step 7 — Pre-construction CCTV inspection. Sydney Water typically requires a CCTV inspection immediately before works commence within the regulated zone. This creates a baseline condition record that protects you if any dispute arises later. Arrange through an accredited drainage contractor and obtain a signed, dated condition report with WRC codes.

Step 8 — Post-construction CCTV inspection. Once works near the asset are complete, commission a post-construction CCTV using the same contractor and reporting format. The report must reference the same asset ID from your BOAA application and include a direct comparison against the pre-construction baseline. Submit to Sydney Water within the timeframe specified in your acceptance letter.

Sydney Water Fees and Charges 2026–27

Sydney Water's fees are regulated by the Independent Pricing and Regulatory Tribunal (IPART) and updated annually on 1 July. The following table summarises the key fees relevant to building over sewer approvals for the 2026–27 financial year (1 July 2026 to 30 June 2027).

In addition to Sydney Water's fees, you must budget for Water Servicing Coordinator charges (market rates, typically $2,000–$5,000 for residential projects), structural engineering fees ($3,000–$8,000 for footing redesign and SEA reports), CCTV inspection costs ($500–$1,200 per inspection), and concrete encasement or bridging works ($5,000–$20,000 depending on pipe size and depth). Infrastructure contributions — payable before the Section 73 Certificate is issued — are calculated based on Equivalent Tenements (ETs) and vary by location. From 1 July 2026, full infrastructure contributions apply, following the phase-out of the transitional 50% cap that was in place during 2025–26.

How Long Does Sydney Water Approval Take?

Approval timelines vary significantly depending on whether your project impacts Sydney Water assets and the complexity of that impact. The key is to start the process early — ideally at concept design stage — so the BOAA assessment runs concurrently with your DA or CDC application.

Section 73 Compliance Certificates: When Do You Need One?

A Section 73 Compliance Certificate is required under Section 73 of the Sydney Water Act 1994 when your development requires a new or modified connection to Sydney Water's water, wastewater, or stormwater systems. This is separate from the Building Plan Approval and is typically needed for subdivisions, dual occupancies, townhouse developments, and any project creating additional dwellings.

The Section 73 process involves four phases: Define (WSC appointed, application made, system capability assessed), Design (WSC prepares designs for Sydney Water review), Delivery (procurement, construction, connections, inspections), and Finalisation (fees, documents, quality control). After applying, Sydney Water issues either a Section 73 Certificate directly (if no works are required) or a Notice of Requirements (NOR) listing what you must complete before the certificate can be issued. The NOR is valid for 12 months — if you don't meet the requirements within that window, you must reapply and pay the application fee again.

Important exemption: granny flats (secondary dwellings) approved under the State Environmental Planning Policy (Affordable Rental Housing) — the AHSEPP — do not require a Section 73 Certificate. However, you still need full Building Plan Approval for any building or excavation work on the property.

Infrastructure Contributions: The July 2026 Full Contribution Transition

One of the most significant cost changes for NSW developers in 2026 is the transition to full infrastructure contributions for Sydney Water. The NSW Government approved a phased transition pathway for drinking water and wastewater infrastructure contributions, and the final step takes effect on 1 July 2026.

Contributions are calculated using Equivalent Tenements (ETs) — one ET represents the annual demand of an average detached single residential dwelling. Your total contribution equals the number of ETs your development represents, multiplied by the price per ET from the relevant Development Servicing Plan, minus any credit for existing usage. Prices vary by service type (drinking water, wastewater, recycled water) and location (different Development Servicing Plan areas across Sydney). There are no transitional arrangements for recycled water or stormwater contributions — full charges have always applied for these services.

Common Mistakes That Derail Sydney Water Approvals

At giantA, we've seen the same patterns repeat across residential and multi-unit developments in Sydney. These are the most common and costly mistakes that project teams make when dealing with Sydney Water assets:

Starting the BOAA process too late. The single most frequent mistake is waiting until after the DA is lodged — or worse, after construction has begun — before engaging with Sydney Water. The correct approach is to trigger the asset enquiry at concept design stage, so both processes run concurrently and you're not left waiting on a technical sign-off before construction can legally start.

Working from outdated utility plans. Rough estimates or old service diagrams lead to wasted design effort. Always obtain a current service location print through Tap In and commission a survey to confirm the exact horizontal position and invert depth of any pipe within 10 metres of your footprint.

Incomplete documentation submissions. Submitting an incomplete package is one of the most common causes of delayed assessments. Your submission must include site plans at minimum 1:200 scale, showing confirmed asset alignment, pipe centreline coordinates, invert depths, manhole locations, and all proposed structures with setout dimensions to the pipe. Footing drawings must have setout dimensions noted explicitly — not left to the reviewer to calculate.

Ignoring construction plant loading restrictions. For pipes with less than 450mm soil cover, no construction plant may pass or be positioned within the zone of influence. Even for pipes with more than 450mm cover, only light construction plants (forklifts, small excavators, wheel loaders) are permitted. Heavy machinery over shallow pipes without protection measures is a breach that can result in Sydney Water issuing a stop-work order under Section 44 of the Sydney Water Act 1994.

How giantA Coordinates Sydney Water Approvals

At giantA, we integrate Sydney Water approval coordination into our standard development workflow. When we take on a project — whether it's a duplex in Merrylands, a townhouse development in Liverpool, or a knockdown-rebuild in Parramatta — we run the BOAA assessment alongside the DA or CDC pathway from day one. Our process includes initial asset identification through Tap In, engagement of qualified Water Servicing Coordinators, coordination of structural engineers for footing redesign, and management of pre- and post-construction CCTV inspections.

In a recent 12-unit townhouse project in Merrylands, we identified a 225mm sewer main running through the rear of the site during the concept design phase. By triggering the BOAA enquiry immediately and running it in parallel with the DA, we compressed what would have been a 14-week sequential process into 5 weeks of concurrent assessment. The structural engineer redesigned the rear footings as a pier-and-beam system that transferred loads clear of the sewer zone, and concrete encasement was specified for a 6-metre section of pipe. The project received Sydney Water acceptance with conditions, and construction proceeded on schedule.

Frequently Asked Questions

Do I need Sydney Water approval if I'm building a granny flat?

Granny flats (secondary dwellings) approved under the AHSEPP do not require a Section 73 Compliance Certificate. However, you still need full Building Plan Approval through Sydney Water Tap In for any building or excavation work on the property. If the granny flat footprint sits within 10 metres of a Sydney Water asset, a detailed BOAA assessment will be required through a Water Servicing Coordinator.

How much does Sydney Water building plan approval cost?

The Building Plan Approval (BPA) fee is $24.15 for the 2026–27 financial year, payable through Sydney Water Tap In. If your project requires referral to a Water Servicing Coordinator, additional market-rate charges apply (typically $2,000–$5,000 for residential projects). Out-of-scope specialist reviews are charged at Sydney Water's hourly rate of $226.83 per hour. Section 73 applications cost $273.70 (CDC pathway) or $723.81 (DA pathway), or $1,202.92 through Developer Direct.

How close can I build to a Sydney Water sewer main?

Minimum horizontal clearance is 1.0 metre for pipes up to 225mm diameter, 1.5 metres for pipes 225–375mm, and 3.0 metres or subject to engineering for pipes over 375mm. Vertical clearance between the underside of your footing and the top of the pipe is typically 300mm minimum, increasing with pipe size and depth. Footings must maintain 600mm clearance from any sewer maintenance structure wall. You cannot build over rising mains, trunk sewers above 375mm, or any asset requiring open maintenance access.

How long does the Sydney Water approval process take?

If there's no impact on assets, approval is instant through Tap In. Minor impacts assessed by a Water Servicing Coordinator typically take 7–21 days. Out-of-scope applications requiring specialist engineering review take up to 42 days for non-complex cases, and 8–12 weeks for complex scenarios. Asset adjustments requiring pipe relocation can take 3–6 months. Start the process at concept design stage to run it in parallel with your DA or CDC.

What happens if I build without Sydney Water approval?

Under Section 44 of the Sydney Water Act 1994, Sydney Water can issue a stop-work order on your site. You may face fines, be required to pay the full cost of restoring damaged assets, and face third-party claims. Your council will not issue a Construction Certificate without evidence of Sydney Water approval, and non-compliant structures may need to be demolished at your cost. Insurance claims for damage caused to Sydney Water assets during unapproved works are typically rejected.

What is a Section 73 Compliance Certificate and when do I need one?

A Section 73 Compliance Certificate, issued under Section 73 of the Sydney Water Act 1994, confirms that your development has met all of Sydney Water's water, wastewater, and stormwater servicing requirements. You need one for subdivisions, dual occupancies, townhouse developments, and any project creating additional dwellings or connections. Granny flats under the AHSEPP are exempt. The certificate is issued after you complete all requirements in your Notice of Requirements and pay any infrastructure contributions.

Can Sydney Water refuse to let me build over a sewer?

Yes. Sydney Water will outright refuse building directly over rising mains (pressure sewers), trunk sewers above 375mm diameter, and any asset listed as requiring open maintenance access. You also cannot build over wastewater property connection points, junctions, or fittings. In these cases, you must relocate your building footprint to achieve the required clearances or negotiate an asset adjustment — though relocation is costly and time-consuming.

What infrastructure contributions apply from July 2026?

From 1 July 2026, full infrastructure contributions apply for drinking water and wastewater services. The transition was phased: 0% in 2023–24, 25% in 2024–25, 50% in 2025–26, and 100% from 1 July 2026. Contributions are calculated based on Equivalent Tenements (ETs) — your development's demand relative to a standard dwelling — multiplied by the price per ET from the relevant Development Servicing Plan, minus any credit for existing usage. Prices vary by location and service type.

Need help coordinating your Sydney Water approval? At giantA, we manage the entire BOAA process — from asset identification through to post-construction CCTV — as part of our integrated design and approval service. Book a free consultation with our team to discuss your project, or call us on +61 488 880 787. We'll identify Sydney Water assets on your site, assess your clearance requirements, and develop a compliant design that keeps your project on schedule.

Sources: Sydney Water Act 1994 (Section 44, Section 73); Sydney Water Building Plan Approvals (sydneywater.com.au); Sydney Water Technical Guidelines ACDP0254 — Building Over and Adjacent to Pipe Assets; Sydney Water Land Development Guide; Sydney Water Other Prices 2026–27; IPART Infrastructure Contributions Determination.