A drainage or sump pump sits in a pit and empties it when the water rises: a stormwater pit in a courtyard, a laundry sump, a lift well, a cellar, or a flooded garage. They look much the same on a shelf, but three things decide whether one works in your pit: how it switches on, what solids it can pass, and what it's made of.
This guide covers the live drainage and sump pumps PSA stocks. For raw sewage, see our separate guide to vortex and sewage pumps.
1. How it switches on
- Manual: no float. It runs when it's plugged in or switched on. Fine for pumping out a flooded area with someone watching, or when a separate controller or float does the switching.
- Tethered float switch (the "1A" versions): a float on a cable that tips up as the water rises. Simple and reliable, but it needs room to swing, so it suits wider pits.
- Vertical float switch (the "AV" versions): a float that slides up and down a rod on the pump. It needs far less width, which is why it suits narrow pits.
- Integrated automatic: the switching is built into the pump body. The most compact option, with nothing to tangle.
If the pit is narrow, choose vertical or integrated switching. A tethered float that catches on the pit wall is the most common reason a sump pump fails to start or doesn't stop.
2. What's in the water
Check the solids rating on the listing against what will actually reach the pit:
- Clearish water with fine silt: the Hyjet HDS stainless range lists maximum suspended solids of 10mm.
- Dirty water with leaves and grit: the Hyjet HV450 passes soft solids up to 15mm, and the DHS series and Pedrollo TEX up to 30mm. These use vortex impellers, where the impeller sits back from the flow, so solids pass without hitting it.
- Sewage or fibrous waste: a drainage pump isn't the right tool. Use a dedicated sewage or grinder pump.
3. Stainless or cast iron
The Hyjet HDS series has stainless 304 body, motor casing, impeller and shaft, with a double mechanical seal in an oil chamber, rated to 10m depth and 40°C. It suits plant room sumps, lift wells and anywhere corrosion is a concern. The Hyjet HV series has a cast iron body with a stainless shaft and vortex impeller, which handles rougher stormwater and greywater well.
The live range at a glance
| Pump | Power | Max flow | Switching | From |
|---|---|---|---|---|
| Hyjet DHS400 | 400W | 156 L/min | Automatic float | $221.05 |
| Hyjet DHS750 | 750W | 200 L/min | Automatic float | $452.05 |
| Hyjet HDS25 (stainless) | 250W | 150 L/min | Integrated or vertical float | $380.55 |
| Hyjet HDS75 (stainless) | 750W | 280 L/min | Integrated or vertical float | $639.05 |
| Hyjet HDS110 (stainless) | 1100W | 330 L/min | Integrated or vertical float | $721.55 |
| Hyjet HV180 (cast iron vortex) | 180W | 133 L/min | Tethered or vertical float | $309.05 |
| Hyjet HV450 (cast iron vortex) | 450W | 200 L/min | Manual, tethered or vertical float | $479.55 |
| Hyjet HV750 (cast iron vortex) | 750W | 300 L/min | Manual or tethered float | $721.55 |
| Pedrollo TEX 2 / TEX 3 | 0.37 / 0.55kW | 200 / 240 L/min | Vertical float | $683.05 |
The Pedrollo TEX is worth a note for tight spaces: its vertical float lets it work in sumps as small as 220mm and it drains to 35mm from the bottom. For a flooded garage or basement, the Pedrollo Plug & Drain kit ($1,354.05) pairs a pump (160 L/min, 9m head) with a 12.5m hose in a carry case that doubles as a filter, and drains to about 2mm above the floor.
Sizing it
- Flow: for stormwater, the pump needs to keep up with the inflow from the area draining to the pit in a heavy storm. Your stormwater design or local council requirements set this.
- Head: add the lift from the pit to the discharge point plus friction in the discharge line, and read the pump curve in the datasheet at that head. Max flow is only achieved at near-zero head.
- Non-return valve: fit one on the discharge so water doesn't run back into the pit every time the pump stops.
- Alarm: in any pit where a failure would flood something, add a high level alarm.
Need the pit too? See Mini Pump Pits for pre-plumbed stormwater pits with a pump fitted. Stormwater and drainage work must comply with AS/NZS 3500.3 and your local authority's requirements.
Frequently Asked Questions
What float switch is best for a narrow pit?
A vertical float or integrated automatic switch. A tethered float needs room to swing and can catch on the walls of a narrow pit.
Can a drainage pump handle sewage?
No. Drainage pumps are for stormwater, greywater and dirty water. Sewage needs a dedicated sewage or grinder pump.
What's the difference between manual and automatic drainage pumps?
An automatic pump has a float switch that turns it on and off with the water level. A manual pump runs whenever it's switched on, so it needs supervision or a separate controller.
Should I choose a stainless or cast iron sump pump?
Stainless (like the Hyjet HDS) suits clean-ish water and corrosive settings like plant rooms. Cast iron vortex pumps (like the Hyjet HV) handle rougher stormwater and greywater with more solids.