Most sewage pumps pass solids whole. A grinder pump cuts them up first, with a hardened cutting system at the inlet, so the pumped sewage is a slurry that fits through a small pipe. That one difference decides when you need a grinder and when you don't.
When a grinder is the right pump
- Small-bore discharge. A grinder can push sewage through a much smaller rising main than a vortex pump, which needs a pipe big enough for solids to pass whole.
- High head or a long run. Lifting sewage a long way up, or over a long distance, is easier with the smaller pipe and higher pressure a grinder works with.
- Pressure sewer systems. Where a property discharges into a pressurised sewer main rather than a gravity sewer, a grinder pump is usually what the system is designed around. Pressure sewer schemes are often run by the water authority, which may specify or approve the pump, so check before you buy.
When a vortex pump is better
If the sewage only needs to lift a few metres into a nearby gravity sewer through a normal-sized pipe, a vortex or channel sewage pump is usually simpler and cheaper to run. There's no cutting system to wear, and solids pass whole. Grinders also need more care with what goes into them: hard objects can damage the cutter.
The Hyjet grinder range
| Pump | Discharge | Power | Supply | Price |
|---|---|---|---|---|
| DTR101 | see datasheet | 1200W (220 L/min, 19m max head) | 240V or 415V | $1,915.05 |
| HWG32-11 | 32mm | 1.1kW | 240V or 415V | $1,816.05 |
| HWG32-15 | 32mm | 1.5kW | 240V or 415V | $2,157.05 |
| HWG32-22 | 32mm | 2.2kW | 240V or 415V | $2,294.55 |
| HWG50-22-3 | 50mm | 2.2kW | 415V | $2,157.05 |
| HWG50-30-3 | 50mm | 3.0kW | 415V | $2,410.05 |
| HWG50-40-3 | 50mm | 4.0kW | 415V | $2,498.05 |
Hyjet HWG: HT200 cast iron casing, stainless shaft and hardened stainless grinding system, double silicon/carbon mechanical seals and an oil-filled motor housing. Listed for homes, restaurants, hotels, farms, municipal lift stations and remote sites. The 1.1kW model comes with a float switch option on single phase; the rest are manual (they need a float or controller to switch them).
Hyjet DTR101: a treated stainless grinder, double seal with an oil barrier and silicon carbide on the pump side, IPX8 motor and 10m cable. Available single phase with or without a float switch, or three phase manual.
Choose by reading the pump curve in the datasheet (under Downloads) at your total head: the lift from the pit to the discharge point plus friction in the rising main.
Installation notes
- Control. Manual pumps need a float switch or a pump controller. See float switches and pump control panels.
- Non-return and isolation valves on the rising main, so the line doesn't drain back and the pump can be removed for service.
- Guide rail for deeper pits, so the pump can be lifted without entering the well. See Guide Rail Kits.
- Alarm: fit a high level alarm to every sewage pit.
- Compliance: sewage pumping must be installed by a licensed plumber to AS/NZS 3500.2 and local authority requirements, and three phase connection by a licensed electrician.
All the pumps above are available to order on backorder; contact PSA to confirm lead time.
Frequently Asked Questions
What does a sewage grinder pump do?
It cuts solids into a slurry with a hardened cutting system before pumping, so sewage can be pushed through a small-bore pipe at higher pressure.
Do I need a grinder pump for a pressure sewer?
Pressure sewer systems are usually designed around grinder pumps, and the water authority may specify or approve the pump. Check with them before buying.
Is a grinder or vortex pump better for sewage?
For a short lift into a gravity sewer through a normal pipe, a vortex pump is usually simpler. For small-bore, high-head or long-distance discharge, a grinder is the better choice.
Do the Hyjet grinder pumps need three phase power?
The 50mm HWG models are 415V three phase only. The 32mm HWG models and the DTR101 are available in 240V single phase or 415V three phase.