Sewage Pump Size Guide: Which Sewage Pump Do I Need?
A sewage pump lifts waste water from a sump, conservancy tank or pump station up to the municipal line, a septic tank or a soak-away. Choosing the right one comes down to three things: what you are pumping, how high and how far you pump it, and your power supply. This guide walks you through each step and shows which pump in our range fits your job. You can also browse all our sewage pumps.
Quick sewage pump chart
| Your job | Pump type | Suggested pumps |
|---|---|---|
| Grey water (showers, basins, washing machines), stormwater or screened effluent | Vortex impeller, 0.55 – 0.75 kW | VXM 0.55 kW (220V), VXM 0.75 kW (220V), VX 0.55 kW (380V), VX 0.75 kW (380V) |
| Raw sewage from a house, flat or cottage, single phase | Raw sewage pump with cutter, 1.1 kW, 50 mm | 50C21.1 1.1 kW (220V) |
| Raw sewage from larger homes, lodges and small complexes, three phase | Raw sewage pump with cutter, 1.1 – 2.2 kW, 50 mm | 50C21.1 1.1 kW (380V), 50C21.5 1.5 kW, 50C22.2 2.2 kW |
| Estates, schools, hotels, factories and farm effluent | Raw sewage pump with cutter, 3 – 7.5 kW, 80 – 100 mm | 80C23.0 3 kW, 80C24.0 4 kW, 100C25.5 5.5 kW, 100C27.5 7.5 kW |
| Municipal pump stations, mines and abattoirs | Heavy-duty channel impeller, 5.5 – 45 kW | B-range raw sewage pumps, sized per project |
| Aggressive or corrosive effluent | Stainless steel sewage pump, 3 kW | WQK25-18-3S (380V), WQK25-18-3S (525V) |
Step 1: Know what you are pumping
- Grey water and screened effluent: water from showers, basins and washing machines, stormwater, or effluent that has already passed through a screen or septic tank. A vortex impeller pump is ideal. The impeller sits back in the housing, so solids up to 35 mm pass through without touching it and clogging is rare. See our vortex pumps.
- Raw sewage: toilet waste, paper and fibrous material straight from the house. You need a raw sewage pump with a cutter. Our C-range pumps have a static cutter that chops fibres before they can wrap around the impeller, and an adjustable bottom plate that keeps them pumping efficiently as they wear.
- Large volumes and big solids: municipal, mining and abattoir pump stations use heavy-duty pumps with a channel impeller, like our B-range.
A drainage pump is not a sewage pump. Drainage pumps are made for clean or slightly dirty water and will block on raw sewage.
Step 2: Work out the total head
Head is how high the pump must push the water, in metres. Measure from the bottom of the sump to the highest point the pipe reaches, then add friction losses for the pipe run. As a safe rule of thumb, allow about 1 m of extra head for every 10 m of pipe, plus a little extra for bends and valves.
Example: a sump 2 m deep, discharging into a municipal line 3 m above ground level, 40 m away: 2 m + 3 m + about 4 m for the pipe = roughly 9 m total head.
Step 3: Make sure the flow keeps the pipe clean
Sewage must move fast enough to carry the solids with it, roughly 0.7 m/s or more in the rising main. As a guide, that is about 5 m³/h in a 50 mm pipe, 13 m³/h in an 80 mm pipe and 20 m³/h in a 100 mm pipe. Choose a pump that still delivers at least this flow at your total head.
Step 4: Check the pump performance
Vortex pumps (grey water and screened effluent)
| Pump | Power | Max head | Head at 6 m³/h | Head at 12 m³/h | Head at 18 m³/h |
|---|---|---|---|---|---|
| VXM10-1 / VX10-1 | 0.55 kW | 7.3 m | 6.4 m | 5.1 m | 3.1 m |
| VXM12-1 / VX12-1 | 0.75 kW | 9.5 m | 8.4 m | 6.9 m | 5.0 m |
C-range raw sewage pumps with cutter
| Pump | Power | Outlet | Max head | Head at 10 m³/h | Head at 20 m³/h | Head at 40 m³/h |
|---|---|---|---|---|---|---|
| 50C21.1 | 1.1 kW | 50 mm | 15 m | 11 m | 7 m | – |
| 50C21.5 | 1.5 kW | 50 mm | 13 m | 11 m | 9 m | – |
| 50C22.2 | 2.2 kW | 50 mm | 17 m | 15 m | 13 m | – |
| 80C23.0 | 3 kW | 80 mm | 21 m | 18 m | 16 m | 11 m |
| 80C24.0 | 4 kW | 80 mm | 24 m | 22 m | 19 m | 14 m |
| 100C25.5 | 5.5 kW | 100 mm | 27 m | 25 m | 21 m | 19 m |
| 100C27.5 | 7.5 kW | 100 mm | 30 m | 28 m | 25 m | 22 m |
Figures are from the manufacturer’s performance data. Pick a pump whose head at your flow is at least your total head from Step 2.
Step 5: Single phase or three phase?
For a normal house on single-phase power, choose a VXM vortex pump (0.55 – 0.75 kW, 220V) for grey water, or the 50C21.1 1.1 kW 220V for raw sewage. The larger raw sewage pumps run on 380V three-phase power, and 525V versions are available on request for mines and industry.
Step 6: Install it properly
- Automatic control: use a float switch or level controller so the pump starts and stops on its own, and add a high-level alarm so you know before the sump overflows.
- Sump size: make the sump big enough that the pump does not start more than about 10 times an hour. Frequent starts wear out the motor.
- Valves: fit a non-return valve and a gate valve on the discharge line.
- Easy servicing: on bigger installations, a duckfoot with guide rails lets you lift the pump out without entering the sump. Duckfoot assemblies for 50 mm to 200 mm pumps are available on request.
- Critical sites: estates, schools and businesses should install two pumps (duty and standby) so there is no downtime.
Keep your sewage system running
Many sewage pump breakdowns are caused by wet wipes, rags and fat. Keep wipes out of the toilets and dose your sump or septic tank regularly with a biological treatment such as Vega Sewage & Fat Destroyer to break down fat and organic build-up. See our full biological range.
Frequently asked questions
What size sewage pump do I need for a house?
For raw sewage from a normal house, a 1.1 kW raw sewage pump with a cutter, such as the 50C21.1, is usually enough if the total head is under about 12 m. If you only pump grey water, a 0.55 – 0.75 kW vortex pump will do.
Can I use a drainage pump for sewage?
No. Drainage pumps are made for clean or slightly dirty water with small particles. Raw sewage contains fibres and solids that will block them. Use a vortex pump for grey water or a cutter pump for raw sewage.
What is the difference between a vortex, cutter and channel impeller?
A vortex impeller sits back in the housing and creates a whirlpool, so solids pass through without touching it, which makes it great for grey water. A cutter chops toilet paper and fibres before they reach the impeller, the right choice for raw sewage from houses and complexes. A channel impeller has large open passages for high volumes and is used in municipal and industrial pump stations.
How high can a sewage pump pump?
Our vortex pumps reach up to 9.5 m, the C-range raw sewage pumps from 13 m up to 30 m, and the heavy-duty B-range up to about 43 m, depending on the model and the flow.
Do you deliver sewage pumps?
Yes, we deliver anywhere in South Africa. Collection in Pretoria is by appointment.
Not sure which pump you need? Send us your lift height, pipe length, pipe size and what you are pumping through our contact page, and we will recommend the right pump.