Drainage for Builders: What You Need to Know
Whether you're managing a residential build, a commercial project, or developing new infrastructure, getting the drainage right is critical. Drainage systems are often overlooked in early planning stages, but they play a key role in site safety, long-term asset performance, and compliance with council and water authority requirements.
In this blog, we'll break down what builders need to know about drainage, from pre-construction assessments to post-build compliance, and how working with a specialist drainage contractor can help ensure the job is done right, on time and on budget.
Why Drainage Matters in Building Projects
Drainage systems aren't just a back-end concern, they affect everything from site access and excavation schedules to landscaping, structural integrity, and handover quality. Poor planning or installation can lead to:
Delays due to water pooling or poor site access
Rework costs due to non-compliant installations
Blockages caused by poor pipe fall or foreign materials
Increased risk of damage during the defect period
Liability issues due to environmental or plumbing failures
When drainage is poorly designed or improperly installed, it can compromise the integrity of the entire build. Issues like backflow, sewer surcharge, or water ingress into foundations can create costly problems for both builders and future occupants.
By prioritising drainage at every stage of the build, you reduce the risk of costly mistakes and streamline your handover process.
1. Pre-Construction Drainage Assessments & Pre-Slab Inspections
Before breaking ground, builders should arrange for a pre-construction CCTV drain inspection, particularly on redevelopment sites. This helps assess the condition of existing infrastructure and confirms whether upgrades, repairs, or full replacements are required.
✅ Why it matters:
Identify existing defects or collapses
Confirm pipe locations and levels
Avoid clashes with proposed structures or landscaping
This step is especially important for subdivisions, knockdown-rebuilds, or when tying into council or water authority infrastructure. It also includes pre-slab inspections, which allow any defects, poor falls, or installation issues to be picked up and resolved before the concrete slab is poured, saving time, money, and rework down the line. It also helps avoid unexpected surprises later in the project that could impact timelines or budgets.
2. Temporary Site Drainage During Construction
Managing stormwater and wastewater during the build is critical. A flooded site can bring construction to a halt, damage materials, or create safety hazards. Even small volumes of standing water can disrupt trades, delay concrete pours, and introduce compliance risks.
✅ Consider:
Site sediment control measures (e.g. silt fencing, drainage pits)
Temporary downpipes and roof drainage during framing
Regular cleaning of open pits and pipes to avoid debris buildup
Ensuring drainage doesn't cause flow onto neighbouring properties
Failing to manage temporary drainage can lead to compliance issues with council or EPA regulations, particularly on environmentally sensitive or sloped sites.
3. Pipe Grading, Alignment & Access
A common issue in new builds is incorrect pipe grading. Pipes that don't have sufficient fall (gradient) may allow water and waste to stagnate, leading to long-term blockages or failed inspections.
✅ Drainage best practice:
Maintain a minimum fall in accordance with AS/NZS 3500 standards
Ensure inspection openings (IOs) are accessible post-build
Avoid sharp bends or unnecessary fittings that may trap debris
Planning access to IOs and pits also matters post-construction. These elements need to remain visible and serviceable—not buried beneath the ground, paving or turf.
4. Post-Installation CCTV Inspections & Post-Slab Compliance
Once the drainage system is installed, verifying that it complies with council, builder warranty, and water authority standards is vital. Many regions now require a CCTV drain inspection before handover to ensure the system has:
Correct fall and alignment
No cracks, displacements or collapses
No debris, grout, or foreign materials inside
✅ When to arrange it:
After the final plumbing rough-in and before pouring driveways
Prior to handover to the developer, council or client
If required as part of subdivision approvals
Ideally, builders should ensure an impartial drainage specialist performs these inspections. Post-slab inspections, in particular, are crucial before pouring driveways or completing external works. They confirm that the system remains intact and compliant after slab construction and catch any inadvertent damage or blockages caused during the slab pour or backfilling process.
5. Repairs & Relining for Damaged Pipes
If damage or misalignment is found during inspection, several repair options are available. For minor issues, high-pressure drain cleaning or grout removal may be sufficient. For more serious defects, pipe relining offers a trenchless solution that avoids the need to dig up finished surfaces.
✅ Why it's builder-friendly:
Minimises project delays
Avoids demolition of concrete or landscaping
Complies with water authority acceptance criteria
Allows repairs to be completed post-handover or during the defects period
Relining is especially useful when damage occurs late in the build or after landscaping is complete. It enables fast, non-invasive rectification, keeping the project moving.
💡 Why Work With a Drainage Specialist?
Not all plumbers or civil contractors offer the same level of expertise in drainage. Partnering with a team that specialises in drain inspections, compliance, and trenchless repairs means:
Faster turnaround and fewer call-backs
Less risk of handover delays
Confidence in defect coverage and warranty integrity
Expert support during defect rectification or client queries
Familiarity with regional standards and council reporting formats
Drainage specialists understand how to keep a site moving while maintaining compliance and build quality. They also help protect your brand and reputation by ensuring post-build drainage systems function as intended.
Final Thoughts: Future-Proof Your Projects
From pre-construction planning to final handover, drainage plays a vital role in the success of every build. By investing in smart drainage practices and working with experienced contractors, builders can reduce risk, save time, and deliver better outcomes for clients.
Drainage should never be an afterthought. It's an integral part of delivering projects that are compliant, efficient, and built to last.
📅 Need CCTV inspections, relining, or builder support? Contact Pipe Doctor today to speak to our drainage specialists and ensure your next project stays on track.
When you have a drainage disaster, you can count on us to get you back up and running.
“Knock, Knock, Pipe Doctor” 1300 747 337
