Stormwater Cost
Estimate the cost of installing or upgrading stormwater drainage on an Australian property, including trenching, pits, pipe and connection to the legal point of discharge.
Measure from the downpipes or problem area to the legal discharge point.
Reinstatement of the surface is often as expensive as the pipe itself.
Junctions, changes of direction and surface collection points each need a pit.
Get a dial-before-you-dig plan before any excavation. It is free, it is a legal expectation before ground disturbance in Australia, and striking a gas, telecommunications or electrical service turns a $4,000 job into a very expensive incident.
💰 Ways to save
- Do the earthworks while other excavation is already happening on site. If you are having a pool dug, a shed slab poured, a retaining wall built or landscaping done, the excavator, the operator and the site access are already mobilised and paid for. Adding stormwater trenching to that program commonly saves $600 to $1,500 in machine hire and mobilisation compared with bringing a machine back specifically for drainage.
- Solve the cause before you buy capacity. A great many stormwater complaints in Australian suburbs are not undersized pipe, they are blocked gutters, a downpipe disconnected from the drain, a sagging gutter, a driveway falling toward the house, or a garden bed built up above the weep holes. A $350 CCTV inspection and an honest look at the surface levels can turn a proposed $8,000 drainage upgrade into a $600 fix.
- Reinstate the surface yourself where you reasonably can. Trenching through lawn is cheap, but topsoil, turf and garden restoration often adds $25 to $60 per metre to a quote. Ask the contractor to backfill and compact properly and leave the finish to you, then lay your own turf or mulch. Do not do this where the trench crosses concrete or paving, because a poor reinstatement there causes settlement and cracking.
- Check whether your council allows on-site infiltration such as soakwells before you assume you need a connection to the main. In much of Perth and parts of South Australia, soakwells are the standard and legal method and are considerably cheaper than a kerb or main connection. In clay-heavy parts of Sydney, Melbourne and Brisbane they often will not be accepted, so confirm early rather than after the pipe is in the ground.
or from $20/week over 5 years , indicative finance
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## What stormwater drainage costs in Australia
Pricing reviewed: June 2026.
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Pricing reviewed June 2026. Indicative Australian costs, not a quote.
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Understanding stormwater costs in Australia
What stormwater drainage costs in Australia
Stormwater work in Australia is generally priced per metre of trench plus fixed items for pits, connections and reinstatement. In 2026 a typical residential run through lawn or garden costs $90 to $160 per metre supplied and installed, including excavation, bedding sand, 90mm or 100mm PVC, backfill and basic reinstatement. Pits with grates cost $250 to $500 each installed. Soakwells run $400 to $900 each depending on size and depth. A straightforward job connecting a few downpipes to a street kerb outlet lands between $1,500 and $4,000, while a full property re-drain with a council main connection commonly reaches $8,000 to $18,000.
The legal point of discharge decides your whole design
Every property in Australia has a legal point of discharge nominated by the local council, and it dictates the design more than any other factor. On a sloping block with a street frontage below the house, gravity does the work and the cost is modest. On a flat block, or one where the house sits below the kerb, the water either has to travel a long way to a rear easement, infiltrate on site, or be pumped, and each of those adds cost. Councils publish the discharge point on a drainage diagram, and asking for it before you get quotes stops contractors from designing three different systems.
Trenching, and why the surface matters more than the pipe
The pipe itself is cheap. A length of 90mm stormwater PVC is a few dollars a metre, and the fittings are similarly modest. What you are paying for is excavation, correct fall, bedding, compaction and putting the surface back the way it was. Trenching through lawn is the cheapest scenario. Cutting through a concrete path adds $80 to $150 per metre for saw-cutting, breaking out, disposal and repouring. Running under an existing driveway is dearest of all, which is why directional boring, at roughly $150 to $300 per metre, is often the cheaper answer despite sounding exotic.
Falls, sizing and the mistakes that cause callbacks
Stormwater relies on gravity, and the standard minimum grade in Australian residential work is about 1 in 100, meaning a 10mm drop per metre of run. Insufficient fall is the single most common cause of a new system that still floods, because water sits in the low points, silt settles and the line progressively blocks. Pipe sizing matters too: 90mm is standard for downpipe connections, 100mm for main runs, and 150mm for larger catchments or where multiple lines combine. Undersized pipe on a large roof area surcharges in heavy rain even when the fall is correct.
Councils, approvals and on-site detention
Requirements vary substantially between councils, so this is one area where local rules genuinely decide your budget. Connecting to a council stormwater main almost always requires an application, an approved plan and an inspection before backfilling, with fees of $300 to $900 and lead times of four to eight weeks. Many councils in growth areas also require on-site detention for new builds or significant additions, which is a tank that holds peak flow and releases it slowly. On-site detention systems commonly add $4,000 to $12,000 and require a certified design and a maintenance schedule registered on title in some jurisdictions.
Licensing, and what is regulated
Stormwater drainage is licensed plumbing work in every Australian state and territory. A licensed drainer or plumber must carry out and certify the work, and connections to council infrastructure typically require a compliance certificate lodged with the relevant authority. Do not accept a landscaper or handyman running new stormwater lines, however capable they are, because unlicensed drainage work is both unlawful and a genuine problem when you sell the property or make an insurance claim after a flood event. Ask for the licence number and check it against your state register.
Where the real value sits
For most Australian homeowners with a water problem, the highest-value first spend is diagnosis rather than construction. A CCTV inspection at $350 to $600, combined with a survey of surface levels and a check of the gutters and downpipes, tells you whether you have a blocked or collapsed line, a disconnected downpipe, a grading problem or a genuine capacity shortfall. Those four problems have wildly different price tags, from a few hundred dollars to five figures, and contractors quoting without that information will reasonably quote the most comprehensive solution.
Frequently asked questions
How much does stormwater drainage cost per metre in Australia?
Typically $90 to $160 per metre through lawn or garden in 2026, including excavation, pipe, bedding, backfill and basic reinstatement. Cutting through concrete adds $80 to $150 per metre, and running under a driveway is the most expensive scenario.
What does a full property stormwater upgrade cost?
Connecting a few downpipes to an existing street outlet usually costs $1,500 to $4,000. A complete re-drain with a new council main connection, multiple pits and surface reinstatement commonly runs $8,000 to $18,000.
Do I need council approval for stormwater work?
For a connection to a council stormwater main, almost always. Expect an application, an approved drainage plan and an inspection before backfill, with fees of $300 to $900 and a four to eight week lead time. Requirements vary by council, so confirm locally before quoting.
What fall does a stormwater pipe need?
The usual minimum residential grade in Australia is 1 in 100, or a 10mm drop per metre of run. Less fall than that lets water and silt sit in the line, which is the most common reason a newly installed system still floods.
Do I need a licensed plumber for stormwater?
Yes. Stormwater drainage is licensed plumbing work in every Australian state and territory, and connections to council infrastructure require a compliance certificate. Unlicensed drainage work creates problems at sale and can jeopardise a flood insurance claim.
How much does a soakwell cost?
Supplied and installed, soakwells typically cost $400 to $900 each depending on diameter, depth and access. They are standard practice in sandy soils such as much of Perth, but many clay-soil councils on the east coast will not accept them as the discharge method.
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