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A flooded cellar, a basement to empty, a bathroom below the level of the sewer: a lift pump sends water up to a higher level. The right model depends first on what you are pumping: clean water, water carrying particles, or wastewater with solids. This guide helps you decide before you look at flow rate and head.
Three liquids, three pump families
This is the most common mistake: buying a pump for its flow rate when it is not designed for the liquid to be removed. A narrow impeller clogs quickly with sand, leaves or fibres. The table below sets out the three families.
| Liquid to remove | Pump family | What to check | Typical cases |
|---|---|---|---|
| Clean or lightly loaded water | Cellar (drainage) pump | Residual water level at start and stop (depending on the model), float type | Flooded cellar, excavation bottom, tank overflow |
| Loaded water (mud, sand, leaves) | Loaded water pump | Solids passage in mm and impeller type, given on the product page | Building site, drainage, runoff, pond |
| Wastewater with solids | Sewage pump or macerator pump | Free-passage impeller or cutting device, discharge diameter, domestic or shared use | Basement toilet or shower, underground kitchen, technical room |
A loaded water pump accepts particles up to a limited size, stated on its product page. A macerator pump cuts up solids before pushing them out, which allows a small-diameter discharge pipe. Even with a macerator, wipes and sanitary products must not be flushed: follow the manufacturer’s instructions.
Single pump or lifting station?
To empty a cellar from time to time, a submersible pump placed at the low point is enough. As soon as drainage is permanent (toilets, kitchen or a basement room), you install a lifting station: a sealed tank that collects the wastewater, one or more pumps, a level control and a check valve.
- One pump: suited to a single discharge point and ordinary domestic use. See the lift pumps and the micro-stations for small volumes.
- Two pumps: the two-pump lifting station works in alternation and the second pump takes over in case of failure or heavy inflow. Preferable where a breakdown is not acceptable (restaurant, shared building, business premises).
- Accessories: a level regulator or a float switch controls start and stop; a check valve stops water flowing back into the tank; a screen filter holds back large debris upstream.
Sizing: flow rate, head and discharge line
Two values are enough to read a pump curve: the flow rate to be removed and the total dynamic head (TDH). TDH is the geometric height between the water level in the tank and the discharge point, plus friction losses in the pipe (length, diameter, bends, check valve). Reminder: 1 bar ≈ 10 metres of water column (mWC) and 1 m³/h ≈ 16.7 l/min. The detailed calculation is explained in the guide Calculating TDH.
On the electrical side, check whether single-phase 230 V or three-phase 400 V is available on site, and choose the discharge pipe with the guide choosing a hose or pipe.
Worked example
A lifting tank whose high water level is 3 m below the discharge point, with friction losses estimated at 2 m, requires a TDH of about 5 m, roughly 0.5 bar. Look on the curve for a pump that delivers the flow you need at 5 m and keep a margin: the maximum flow rate advertised is often quoted for a much lower head. A discharge line that is too long or too narrow noticeably reduces the real flow.
The mistake to avoid
Installing a cellar pump to remove toilet or kitchen wastewater. Its impeller is not designed for solids: it clogs, the pump overheats and stops. If you are unsure about the nature of the water, choose the next family up.
The selection method in 5 steps
- Identify the liquid: clean water, loaded water or wastewater with solids.
- Estimate the volume and frequency: occasional emptying or permanent drainage.
- Calculate the TDH: discharge height plus friction losses, in metres of water column.
- Choose the model from its curve, its solids passage and its power supply (230 V or 400 V).
- Complete the installation: level control, check valve, isolation valve and, if needed, a second standby pump.
Frequently asked questions
What is the difference between a cellar pump and a loaded water pump?
A cellar pump is designed for clean or very lightly loaded water and can pump down to a low water level. A loaded water pump lets larger particles through thanks to its impeller and wider passages; the permitted size is given on the product page.
Do I need a macerator pump?
It is useful when the water contains solids (toilets) and you want a small-diameter discharge or drainage over a long distance or a large height. For water that is simply loaded with particles, a free-passage pump is enough.
Can a lift pump run from a battery?
Yes for some uses: there are 12 V or 24 V models, useful on a boat or where there is no mains supply. See the 12 V / 24 V lift pumps.
Going further
Choosing a sewage pump stationOne or two pumps, tank, lifting height.Lift pumpsAll the pump families for removing clean, loaded or waste water.Lifting stationsTank, pump(s) and level control ready to connect.Cellar pumpsTo empty a cellar or an excavation bottom.Calculating TDHMethod and worked example for reading a pump curve.Choosing a hose or pipeDiameter and type of pipe for your discharge line.