French Drain Installation Cost Calculator & Price Guide
Use this French Drain Installation Cost Calculator & Price Guide to estimate what you might pay for french drain installation in Australia. Most french drain installation cost estimates range from $100 to $250 per linear metre (AUD), depending on site conditions, excavation method and whether soakwells are included.
Estimate French drain installation cost
Supply-and-install midpoints for an agi or subsoil drain in Australia. A standard backyard job is usually $1,500 to $5,000, and rates sit inside $50 to $400 a lineal metre (NSW about $50 to $150, Victoria $50 to $120, Queensland $60 to $150, Western Australia $150 to $400, often with soakwells). Clay, depth over 600 mm, hand digging, or a stormwater connection (a licensed plumber at $80 to $120 or more an hour, and sometimes a council permit) costs more. DIY materials are about $30 to $60 a metre.
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French Drain Installation Price Breakdown
Typical job based on 20 lm. Prices are supply-and-install midpoints — actual quotes will vary.
| Type | Cost per lm | Typical 20 lm job |
|---|---|---|
| Standard agi drain | $100 | $2,000 |
| Clay soil or deeper than 600 mm | $140 | $2,800 |
| Hand dug | $200 | $4,000 |
| With soakwells | $250 | $5,000 |
What Affects French Drain Installation Cost?
- Drain type: The base price for a standard agi drain is $100 per linear metre. This is the lowest-cost option and is often used as the starting point for estimating.
- Soil conditions and depth: If the job is in clay soil or needs to be dug deeper than 600 mm, pricing increases to $140 per linear metre. Harder digging conditions and extra depth usually mean more labour and time on site.
- Excavation method: Hand dug french drain installation costs more because it is slower and more labour-intensive than machine excavation. Hand-dug work is priced at $200 per linear metre.
- Soakwells: Adding soakwells raises the total cost because the drainage system becomes more complex and requires extra installation work. Jobs with soakwells are priced at $250 per linear metre.
French Drain Installation Cost - Frequently Asked Questions
French drain installation cost is $100 per linear metre for a standard agi drain, $140 in clay or deeper than 600 mm, $200 when the trench is dug by hand, and $250 with soakwells. A typical 20 metre standard agi drain has a midpoint of $2,000. The same length is $2,800 in clay or a deeper trench, $4,000 if it is dug by hand, and $5,000 with soakwells. The calculator shows about 15% either side of the midpoint, and jobs that calculate under $1,500 use a $1,500 minimum.
Using the default 20 lm example, a standard agi drain is based on a midpoint of $2,000 AUD, while clay soil or deeper than 600 mm is $2,800 AUD. A hand-dug drain comes to $4,000 AUD, and a system with soakwells is $5,000 AUD. The displayed estimate range is calculated at ±15% around those midpoint figures.
Clay soil or a trench deeper than 600 mm is priced at $140 per linear metre, compared with $100 per linear metre for a standard agi drain. These conditions generally make excavation and installation more difficult, which increases labour time. On a 20 lm job, that changes the midpoint from $2,000 AUD to $2,800 AUD.
Hand-dug french drain installation is priced at $200 per linear metre. For a 20 lm job, the midpoint cost is $4,000 AUD, with the calculator displaying a range of ±15% around that figure. This option is usually chosen where machinery access is limited.
French drain installation with soakwells is the highest-priced option at $250 per linear metre. For a typical 20 lm installation, the midpoint cost is $5,000 AUD, and the displayed estimate range is ±15%. This reflects the added work involved in connecting the drain to soakwells.
Yes, the minimum job charge is $1,500 AUD when the per-metre maths would otherwise come in lower. For example, smaller jobs calculated from the $100 per linear metre rate may still be lifted to the $1,500 AUD minimum. This ensures very short drain runs still meet the minimum service cost.
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