Pumps and dewatering equipment keep excavations dry, bypass sewers and stormwater, empty flooded sites and move process water. The right pump depends on the flow rate required, total head (vertical lift plus friction losses) and what the water carries—clean water, silt, slurry or solids.
Excavations below the water table may need wellpoint or spear dewatering systems rather than a single sump pump. Discharge often requires treatment, sediment control or approval before release to stormwater or sewer.
Diesel self-priming pumps suit sites without power; electric submersibles suit continuous duty where power is available. Automatic start/stop, float switches and telemetry reduce the risk of overnight flooding.
Pumps & dewatering classes and sizes
The table below lists the classes of pumps most commonly available for hire in Australia. Exact specifications vary by make and model—confirm dimensions, weight and capacity with the supplier before booking.
| Class | Size / spec | Typical jobs |
|---|---|---|
| Submersible drainage | 50–150 mm | Sumps, pits, flooded basements |
| Self-priming trash pump | 50–150 mm diesel | Dirty water with solids, trench dewatering |
| High-head / fire-fighting | High pressure | Long discharge runs, fire support |
| Wellpoint system | Spears + header + pump | Lowering groundwater in sandy soils |
| Sewer bypass pump | 100–300 mm | Maintaining flow during pipe works |
How to choose the right machine
Know flow and head
Estimate litres per second, the vertical lift and discharge length. Head decides whether a pump can deliver the flow you need.
Describe the water
Silt, sand, sludge and solids wear pumps and require suitable impellers and hose sizing.
Plan discharge
Arrange settling, sediment control and approvals before discharging to drains or sewer.
Guard against failure
Critical dewatering needs standby pumps, auto-start and alarms.
Licences, tickets and compliance
- Discharging site water to stormwater or sewer usually requires approval from council, the water authority or the environmental regulator.
- Diesel pumps require bunding and spill kits near waterways.
- Deep excavations with groundwater need geotechnical input on stability and settlement risk.
See our plant licences and tickets guide for the full list of High Risk Work Licence classes.
What drives the cost
The hire rate is only part of the total. On short hires these items often add 20–50% to the bill—ask every supplier to quote them the same way:
- Pump size and run hours
- Hose, fittings and discharge length
- Wellpoint installation labour
- Fuel and monitoring
- Treatment tanks and testing
For indicative 2026 rates, see the plant hire cost guide.
Where it fits in a project
- Mobilise flood recovery — Sequence access assessment, pumping, debris handling and road restoration while conditions remain unstable.