Soakwells Perth: Supply & Install
Perth's sandy soil is naturally free-draining, but every new build and major renovation must manage stormwater on site under local council and Water Corporation rules. Soakwells are the standard solution, and sizing them correctly is the part most people get wrong.
Soakwell supply, excavation and installation in one service
Sized to your block area and council specifications
PC18 mini for tight access, PC55 for larger tanks
50+ jobs completed across Perth metro
Why Perth Requires Soakwells
Perth councils require new buildings and major extensions to retain a set volume of stormwater on site. The standard approach is a soakwell pit filled with a polypropylene tank, installed below ground and connected to roof downpipes.
Perth's predominantly sandy subsoil is well-suited to soakwells. Water drains from the tank into the surrounding sand quickly, which means a correctly sized soakwell handles even heavy summer thunderstorms without backup.
We supply and install soakwells across Perth. That means we excavate the pit with the right machine for your access, drop in the correct size polypropylene soakwell, backfill, connect the downpipe inlet and leave the site ready for compaction or paving.
The Komatsu PC18 1.8t mini excavator handles most residential installations, fitting through a 900mm gate and working in tight side passages. For larger tanks or difficult ground, the PC55 gives us more lift and more reach.
The Perth Sand Advantage
- Stormwater floods across your site and your neighbour's property
- Building completion certificate or occupation permit may be withheld
- Retaining walls and footings can be undermined by unmanaged stormwater
- Council can require rectification works at significant cost
Sizing Is Set by Council Rules
Most Perth local governments follow a standard sizing formula based on the impervious roof area and a rainfall intensity figure. Get this wrong and the soakwell overflows during heavy rain. We size soakwells to council specification so you do not need to work out the formula yourself.
How Soakwells Are Sized in Perth
125L
Per m2 Roof Area
Standard Perth council sizing formula
900mm
Minimum Gate Width
For PC18 access to tight residential lots
1.5m
Common Install Depth
For 1,200L-2,400L residential soakwells
1 day
Typical Install Time
For 1-4 soakwells on a standard residential block
| Tank Size (litres) | Common Application | Approx. Pit Depth |
|---|---|---|
| 600L | Small downpipe run, garage roof section | ~1.0m |
| 1,200L | Average residential downpipe catchment | ~1.2-1.5m |
| 2,400L | Large roof area or combined catchment | ~1.5-1.8m |
| 4,800L+ | Commercial or large impervious area | ~2.0m+ |
Common soakwell sizes and approximate applications (indicative only)
Soakwell sizing in Perth is based on the total impervious area (roof plus hard surfaces draining to the soakwell) and a design rainfall rate. The standard used by most councils is 125 litres per square metre of impervious area.
Multiple smaller soakwells connected in series can substitute for one large tank, which is useful where access restricts the size of tank we can lower into the pit.
The Anatomy Of A Soakwell
A soakwell is simple once you see it in the ground. Stormwater comes off the roof, runs down the downpipe and into a perforated tank buried in the sand.
From there the water seeps out through the tank walls and disperses into Perth's free-draining subsoil, well away from your slab, paving and footings.
Cutaway view, not to scale
- 1
Roof Downpipe Inlet
Stormwater off your roof runs straight in through the connected downpipe.
- 2
Polypropylene Soakwell
A lightweight tank, sized to your roof area and your council's spec.
- 3
Perforated Walls And Lid
Slots release the water evenly into the ground on every side of the tank.
- 4
Free-Draining Perth Sand
Our sandy subsoil soaks the water away fast, even in a summer downpour.
- 5
Compacted Sand Bedding
A level, compacted base keeps the tank sitting true for the long haul.
How the Soakwell Installation Works
Quote and Sizing
You call us with the roof area, access details and the number of downpipes needing soakwells. We size the tanks to council spec and give you an all-in price for supply and install.
Services Located
We locate underground services via Dial Before You Dig and confirm the safe dig zones before any excavation begins.
Pit Excavation
The PC18 or PC55 excavates the soakwell pit to the required depth and diameter. Spoil is stockpiled alongside for backfilling.
Tank Lowered and Bedded
The polypropylene soakwell tank is lowered into the pit and bedded on compacted sand. We position the inlet port to align with the incoming downpipe run.
Backfill and Compact
The pit is backfilled with the excavated sand and compacted. The inlet is connected to the downpipe run, ready for the plumber to tie in the downpipe.
“We dig, supply and install. You tell us the roof area and the access, and we handle the rest.”
Plant Hire Perth
Call us direct - most enquiries answered within the hour.
Soakwell Supply and Install Pricing
| Soakwell Size | Indicative Installed Price (from) | Notes |
|---|---|---|
| 600L single tank | Call for quote | Small catchment areas |
| 1,200L single tank | Call for quote | Typical residential downpipe |
| 2,400L single tank | Call for quote | Larger roof areas |
| Multiple soakwells (connected) | Call for quote | Site-specific pricing |
Soakwell pricing depends on the number of tanks, tank sizes, ground conditions, access difficulty and transport distance. We give you a fixed supply-and-install price so you know the cost before we start.
All-In Supply and Install
Our soakwell service includes machine hire, operator, supply of the polypropylene tanks, excavation, bedding, backfill and inlet positioning. You arrange the downpipe connection with your plumber. One call to us covers the dig and the tank.
The Komatsu Fleet You Can Put To Work
Excavator Hire
Komatsu PC18 (1.8t) · PC55 (5.5t) · PC138 (13.8t)
Komatsu PC18, PC55 and PC138 diggers, 1.8t to 13.8t for any job size.
Excavator Hire
Mini Excavator Hire
Komatsu PC18 (1.8t) · rock breaker · plant trailer included
Komatsu PC18 1.8t for tight backyard and side access, rock breaker available.
Mini Excavator Hire
Bobcat Hire
Bobcat T450 · T590 · 4-in-1 buckets
Bobcat T450 and T590 skid steers with 4-in-1 buckets for levelling and clean-up.
Bobcat Hire
Tipper Truck Hire
8t Isuzu FVR tipper
8t Isuzu FVR tipper for soil, sand and spoil cartage.
Tipper Truck HireRelated Hire & Services
Trenching & Drainage Perth: Services & Utilities
Trenching for pipes, cables, drainage and stormwater across Perth. Komatsu excavators with trained operators. Fast quotes and on-site response.
Trenching & Drainage Perth
Excavation & Earthworks Perth: Site Cuts & Pads
Excavation and earthworks across Perth - site cuts, house pads and bulk earthmoving. Komatsu excavators with trained operators. Get a fast quote.
Excavation & Earthworks Perth
Mini Excavator Hire Perth: 1.8t Tight Access
Mini excavator hire Perth - Komatsu PC18 1.8t for tight backyards and side access. Rock breaker available. Wet or dry hire, call us now.
Mini Excavator Hire PerthSoakwells Perth Questions
Soakwell installation pricing in Perth depends on tank size, the number of soakwells, access to your property and ground conditions. Call us for a fixed supply-and-install quote based on your specific block and roof area.
Most Perth councils use a formula of 125 litres per square metre of impervious area. For a standard 150m2 roof draining to one soakwell, you would need around 1,875L capacity. We size soakwells to your council's current specification when we quote.
Yes. The Komatsu PC18 mini excavator is 800mm wide and fits through a standard 900mm gate. It can dig soakwell pits in most Perth residential backyards and side passages.
Yes. Our service includes supply and installation of polypropylene soakwell tanks. We size them, supply them and install them. You connect the downpipes through your plumber.
Soakwells installed as part of a building permit are typically covered by the development approval. Standalone soakwell replacements on existing properties usually do not require separate approval, but check with your local council if unsure.
Need Soakwells In Perth?
We prefer calls, get straight through to the team. Reliable machines. Experienced operators. Jobs done right.