19 October 2026 Uncategorized 0

Drainage Core Drilling: Planning Holes for Pipes and Stormwater

Drainage core drilling is the process of cutting clean, round holes through concrete slabs, walls, kerbs and footings so that stormwater, waste or discharge pipes can pass through. A diamond-tipped bit removes a solid cylinder of concrete, which leaves a smooth-walled opening that is easy to seal and sized to your pipe. Done well, it takes minutes per hole. Done badly, it can cut a post-tension cable, flood a basement or leave a pipe at the wrong fall. This guide explains how the job works, what to settle before drilling day and what to ask your contractor.

Vicsawing

Plan Drainage Holes With Confidence

Vic Sawing & Drilling provides concrete core drilling and scanning across Melbourne and Victoria for drainage and other pipe penetrations.

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TL;DR

Drainage holes are cut with a water-cooled diamond core bit. Wet drilling keeps silica dust down and gives the cleanest hole.
Scan the slab for reinforcement, post-tension cables and conduits before you mark a single hole. Drawings alone are not enough.
Set the position, diameter and fall of the pipe first. In new slabs-on-ground, penetrations are best set before the pour, because changing them later costs more.
In Victoria, cutting concrete is regulated for crystalline silica, and commercial sites often require a SWMS and a permit-to-cut.
We drill and scan across Melbourne and Victoria, and you can request a free quote for your job.

What drainage core drilling is used for
Why coring beats a jackhammer or a chisel
Plan the hole before anyone drills
Scanning: find what is inside the slab first
Wet drilling and silica: the safety side
Commercial sites: permits and paperwork
Perspective: what we see on drainage jobs
How the job runs, step by step
What affects the price
Get drainage holes cut right
FAQ
Sources

What drainage core drilling is used for

A core drill spins a hollow, diamond-segmented barrel against the concrete. Tyrolit describes the process as removing a cylindrical section from concrete, masonry or stone at a controlled speed. For drainage, that cylinder is the pipe path.

Typical drainage jobs include:

Stormwater and downpipe connections through footings, retaining walls and kerbs.
Floor waste and sanitary pipe penetrations through suspended slabs in apartments and commercial buildings.
Discharge holes from planter boxes, podiums, plant rooms and car park slabs.
Retrofit drainage in existing buildings, where a new bathroom, kitchen or floor grate needs a path through the slab.
Sump, pit and pump connections in basements and industrial floors.

The same method suits electrical conduits and air-conditioning lines, so a plumber, an electrician and a drainer may all need holes in the same slab. Coordinating them in one visit saves mobilization time. See our guide to concrete drilling for electrical and plumbing installations for how those trades overlap.

Why coring beats a jackhammer or a chisel

Breaking a hole with a hammer leaves a ragged opening, cracks the surrounding slab and exposes reinforcement you may not want exposed. Coring leaves a precise edge. According to 2026 industry guidance from Tyrolit, it works three to five times faster than chiselling while keeping tight control over the surrounding structure.

For drainage, the clean edge matters in three practical ways:

A round, smooth hole is easier to seal around the pipe with a sleeve, collar or non-shrink grout.
The pipe can be set at the exact angle and fall the design calls for.
There is less patching, which matters in waterproofed areas where every extra repair is a potential leak.

Plan the hole before anyone drills

Most coring failures begin before the drill is switched on. Tyrolit’s guidance says most failures trace back to poor site preparation, such as not checking concrete strength and reinforcement details first. For drainage work, settle these points in advance.

Diameter and pipe sizing

The hole needs to be larger than the pipe so you can fit a sleeve, seal or fire collar, but not so large that it weakens the slab or wastes grout. Confirm the pipe’s outside diameter and any collar size with your plumber or drainer, then give your concrete cutter the finished hole size, not the pipe size. Hand-held rigs suit holes up to about 152 mm, while track-mounted rigs handle 25 to 600 mm. Larger stormwater holes usually need a stand-mounted rig anchored to the slab.

Position, fall and angle

Gravity drainage depends on fall. Guidance for Australian owner-builders points to a typical fall of 1% and rocker pipes at entry and exit points of rigid structures to allow for ground movement. That affects where the hole sits. A hole drilled 100 mm too high on a footing can leave the pipe without enough fall on the far side. Mark the invert level (the bottom inside of the pipe) rather than the centre of the hole, and check it against the drainage plan.

Standards and approvals

Stormwater work in Australia refers to AS/NZS 3500.3, and the Plumbing Code of Australia refers extensively to AS/NZS 3500. In Victoria, drainage connections are a licensed plumbing matter, so the hole is only one part of the work. Your plumber or drainer defines the requirement, and we cut to it. If the slab is structural, an engineer should approve any penetration near beams, columns or edges.

If you are also planning waterproofing around a below-grade penetration, this below-grade waterproofing guide from a South African contractor explains the principles of sealing foundation walls and slabs. Local codes differ, so use it for the thinking, not the specification.

Scanning: find what is inside the slab first

Concrete hides reinforcement bars, electrical conduits, water services and, in many modern slabs, post-tension tendons. Original drawings often miss changes made during construction. Professional operators use ground-penetrating radar to find post-tension cables and live conduits, and the same source warns that striking a post-tension cable can cause significant structural failure.

WorkSafe Victoria’s industry standard likewise classes concrete drilling as high risk, citing silica dust, vibration, electrical hazards and possible collapse if rebar or tension cables are severed.

What that means in practice:

Scan before you mark, not after. Moving a hole 150 mm is free on paper and expensive once drilled.
If the scan shows a cable or conduit in the way, shift the hole. Do not “just try it”.
Mark the scan results on the slab so every trade sees them.

We offer concrete scanning alongside drilling on our main services page. For tendons specifically, read our article on drilling near post-tensioning tendons.

Wet drilling and silica: the safety side

Cutting concrete releases respirable crystalline silica. WorkSafe Victoria states the workplace exposure standard is 0.05 mg/m³ as an 8-hour time-weighted average, and recommends going lower, below 0.02 mg/m³, to reduce the risk of silicosis and lung cancer. The same page requires on-tool water suppression or dust extraction, and slurry must be managed so it cannot dry into hazardous dust.

For core drilling, that makes wet drilling the sensible default. Continuous water suppresses dust at the source, cools the diamonds and flushes debris from the hole. Dry coring is reserved for situations where water is not feasible, such as indoor masonry, and then only with certified dust extraction.

That brings a drainage-specific question: where does the slurry go? Slurry from a core drill is a concrete-laden liquid, and it must not wash into stormwater pits. Good crews:

Use a vacuum ring or wet vac to capture water at the bit.
Block nearby floor wastes and pits before drilling.
Collect and remove the slurry, or let it settle in a contained area for disposal as required.
Bring their own water supply, since a site tap that loses pressure midway is a common reason for jagged, failed holes.

On the equipment side, the same guidance mentions that reinforced concrete needs lower bit speeds (300 to 400 RPM) than plain concrete (450 to 600 RPM). If the slurry turns gray and thick, the bit is probably meeting steel and the operator should ease off speed and pressure.

Commercial sites: permits and paperwork

On commercial and industrial sites, expect a formal process. According to Baseline’s site standard, penetrations deeper than 50 mm in existing slabs often need a permit, and subcontractors who skip the permit-to-cut risk work stoppages. Their guidance suggests submitting a Safe Work Method Statement (SWMS) and getting site manager approval at least 7 days before starting. Each site sets its own rules, so ask your head contractor for theirs.

A realistic pre-start checklist:

Item	Who usually provides it
Drainage plan with hole positions, sizes and inverts	Designer or drainer
Slab scan results	Concrete scanning operator
SWMS and permit-to-cut	Concrete cutting contractor and site manager
Structural approval near beams or edges	Engineer
Water and slurry control plan	Concrete cutting contractor
Access, power and working hours	Head contractor or property manager

Perspective: what we see on drainage jobs

We cut and drill concrete for builders, plumbers, property managers and homeowners across Melbourne and Victoria, from small domestic holes to large construction projects. Drainage jobs look simple, but the ones that go wrong tend to share a cause: the hole was positioned from a drawing, not from the slab.

Our advice is consistent. Scan first. Agree the finished hole size with the plumber before we arrive. Tell us if the slab has waterproofing, in-slab heating or a fire rating, because each changes how we drill and how the hole is sealed. And make sure the access is clear, since a rig that cannot sit square to the slab cannot drill square.

We also prefer to be called early. A penetration set at design stage costs very little. The same hole requested the day before the plumber arrives, with no scan and no permit, puts everyone under pressure. Our licensed and qualified operators work to OH&S standards on every job, and we would rather rearrange a start time than rush a hole through a slab we have not checked.

— MYBMC

How the job runs, step by step

Brief and quote. Send us the drawing or photos, hole count, diameters, slab thickness and access details. We confirm what we can and what needs a site visit.
Scan and mark. The slab is scanned and positions marked, with inverts and angles checked against the plan.
Set up. The rig is anchored by bolt or vacuum so the bit stays vertical or at the required angle. A stable setup is what gives you the verticality needed for a pipe to fit properly.
Control water and slurry. Pits and wastes are protected, and water is captured at the bit.
Drill. The operator holds steady feed pressure and a consistent water flow. A typical flow is 2 to 4 liters per minute for most jobs.
Remove the core and clean up. The plug is extracted, the hole checked for size and the slurry removed.
Hand over. Your plumber or drainer installs the pipe and seals the gap.

For deep holes, see how deep you can core drill concrete in our explainer. If space is tight, our piece on drilling in tight spaces covers the options.

What affects the price

We do not publish a price for core drilling because each job differs. Our published range for one-off concrete cutting jobs is $450 to $5,000, which gives a sense of scale, but a drainage coring quote depends on:

Number and diameter of holes.
Slab or wall thickness and reinforcement density.
Access, height and whether a rig can be anchored.
Whether scanning is needed.
Water, slurry and dust control requirements.
Working hours, such as out-of-hours work in occupied buildings.

The cheapest way to save money is to group all holes into one visit and finalize positions before we arrive.

Get drainage holes cut right

If you need holes cut for stormwater, floor wastes or discharge lines in Melbourne or elsewhere in Victoria, our team can scan, drill and clean up in one visit. Read about our core drilling service, or send us the plans and request a free quote through our main site. If the job also involves removing a section of slab, see our concrete removal service.

FAQ

Can I core drill through concrete myself for drainage?

The equipment exists, but we do not recommend it for drainage work. Unscanned slabs can hide cables and conduits, and silica rules apply to anyone cutting concrete. Connecting to stormwater also involves licensed plumbing work. Hiring a professional for the hole, and a licensed plumber for the pipe, is the safer route.

How much does it cost to core through concrete?

It depends on diameter, thickness, reinforcement, access and scanning. Our published range for one-off concrete cutting jobs is $450 to $5,000, but core drilling is quoted per job. Send us your hole schedule and we will give you a free quote.

Is wet or dry drilling better for drainage holes?

Wet drilling is the standard choice. Water suppresses silica dust, cools the bit and flushes debris. Dry drilling is only for cases where water is not feasible, and then it needs certified dust extraction. Slurry from wet drilling must be kept out of stormwater pits.

Do I need a permit to core drill a slab?

On many commercial and industrial sites, yes. Deeper penetrations in existing slabs often need a permit-to-cut and a SWMS approved by the site manager, ideally about 7 days ahead. Residential jobs are usually simpler, but a structural slab still needs an engineer’s view if the hole is near beams or edges.

Should holes be cored before or after the slab is poured?

Where you can, plan penetrations before the pour. For slabs-on-ground, changes after the pour are costly and risk damaging the slab. Cored holes still suit retrofits and design changes.