Your cart
There are no more items in your cart
A flooded cellar, a garage below street level, a crawl space full of water: a cellar pump moves water from a low point to the outside. The right model depends on the water to pump (clean or loaded), the depth of water you accept to leave on the floor and how the pump is switched (built-in float, external float or manual). Here is how to choose without mistakes.
How does a cellar pump work?
A cellar pump sits at the lowest point of the room. It is submersible: water enters through the intake under the pump, the impeller sets it moving and pushes it through the discharge hose to the outlet. As the pump is already in the water, it does not need priming. The float starts it when the water rises and stops it when the level drops, which makes the pump automatic.
Clean water, loaded water or floor suction?
A cellar pump is a submersible pump placed on the floor. Start from the liquid to remove and the water level you want to reach.
| Need | Pump type | What to check |
|---|---|---|
| Clean or very slightly loaded water | Cellar pump | Particle passage and flow, stated on the product page |
| Dry the floor almost completely | “Floor-suction” model (pumps at low water level) | Minimum residual water level of the model, stated on the product page |
| Mud, sand, leaves, site water | Loaded water pump | Size of particles accepted, type of impeller |
A cellar pump is not designed for waste water with solids (toilets, kitchen): see the guide choosing a lift pump and the lift pumps.
Cellar pump or lift pump: what is the difference?
A cellar pump is portable: you place it on the floor to empty a cellar, garage or sump, occasionally, with clean or slightly loaded water. A lift pump is installed permanently, in a tank or a station, to move loaded water or waste water continuously to a network located higher up. For an occasional drying job, choose a cellar pump; for permanent drainage, see our lift pumps.
Built-in float, external float or no float
The float is the switch that starts the pump when the water rises and stops it when the water drops. It is what makes a cellar pump automatic.
- Built-in float: the switch is part of the pump (as on the Pedrollo TOP 2, for example). It is simple to set up, with no accessory to fit.
- External float: the switch is separate from the pump body or mounted beside it, and its type (vertical, cable) is stated on the product page. Some kits offer an adjustable float to set the switch-on level.
- No float: the pump is started and stopped by hand, or by a separate level control. Keep an eye on it: a pump running dry can be damaged.
In every case the float must move freely, without touching the wall or the cables. Check the switch type on the model’s page.
Sizing: flow, head and hose
Two values are enough to read a pump curve: the flow to remove and the total dynamic head (TDH). TDH is the height between the pump and the discharge point, plus the friction losses in the hose (length, diameter, bends). Conversions: 1 bar ≈ 10 mWC and 1 m³/h ≈ 16.7 l/min. The detail is in the guide calculating total dynamic head.
The discharge hose should have a diameter at least equal to the pump outlet: a narrower, longer hose with many bends reduces the flow. To choose it, see choosing a hose or pipe.
Worked example
Assumptions: a 4 m × 5 m cellar (20 m²) with 10 cm of water, about 2 m³ (2,000 litres) to remove. The outlet is 3 m above the cellar floor, with 10 m of hose: allow about 1 m of friction losses, a TDH of about 4 m. To empty it in half an hour you need 2,000 l ÷ 0.5 h = 4 m³/h at 4 m head. Look for a pump that gives this point on its curve, with a margin.
Example model: the Calpeda GXRM GFA (stainless steel 304 body and impeller, vertical float switch, 230 V single-phase, 1" 1/4 female outlet) comes in three ratings: 0.25 kW (max flow 10.2 m³/h, max head 9 m), 0.37 kW (12 m³/h, 11 m) and 0.45 kW (13.2 m³/h, 12.7 m). The maximum flow is given at low head: read the flow at 4 m on the manufacturer’s curve before you choose. These calculation values are assumptions, to adapt to your cellar.
The mistake to avoid
Buying a clean-water pump to remove muddy or sandy water: the impeller wears or clogs. Another common trap: a float jammed against the sump wall, which stops the pump from starting or stopping.
Reading the flow rate: l/h or m³/h?
Product sheets give the flow in litres per hour (l/h) or cubic metres per hour (m³/h): 1 m³/h = 1,000 l/h, so a 9,000 l/h pump delivers 9 m³/h. This figure is the maximum flow, measured at low discharge head: it falls as the head rises. Always compare the flow with the head you need on the manufacturer’s curve, as in the worked example above.
Installation in brief
- Place the pump on a stable surface, at the lowest point.
- Run the discharge hose to an authorised drain (local sanitation and rainwater rules).
- On a long or rising discharge, a non-return valve stops the water running back into the cellar at each stop.
- Power the pump from a compliant electrical installation with residual-current protection, and follow the manufacturer’s instructions.
My cellar pump will not start or has stopped pumping: what should I check?
Unplug the pump before any work, and take it out of the water to check it.
- The power supply: socket, extension lead, circuit breaker or residual-current device tripped.
- The float: stuck against the wall, a cable or an obstacle, it no longer operates the switch.
- The intake: sand, mud, leaves or small debris can block the strainer or the impeller; clean them out.
- The discharge hose: a kinked, blocked or frozen hose, or a stuck check valve, stops the water from leaving.
- Thermal protection: after overheating or running dry, the motor may stop by itself; let it cool down.
- A pump that runs without delivering may hold air or have a worn or blocked impeller: follow the manufacturer’s instructions.
If the problem remains, call us on +33 3 44 25 91 01.
The selection method in 5 steps
- Identify the water: clean, slightly loaded or muddy.
- Set the level to reach: almost dry floor (floor suction) or a few centimetres of water accepted.
- Calculate flow and TDH from the volume, the time you want and the hose route.
- Choose the control: built-in float, external float or manual.
- Check electrics and hose: current on the product page, outlet diameter, non-return valve, authorised drain.
Which cellar pump for which need? Our models
- Loaded water, stainless steel, with float: the FPX 50/32 M (vortex impeller, particles up to 20 mm, 10.5 m3/h);
- Stainless steel, three power ratings: the Calpeda GXRM GFA (0.25, 0.37 or 0.45 kW);
- Nearly dry floor: the Pedrollo TOP 2 FLOOR (suction down to 2 mm, versions with or without check valve);
- Small domestic use: the Pedrollo TOP 2 (0.37 kW) or the Calpeda GM10 (vortex impeller, float switch, 0.30 kW);
- Ready-to-fit kit: the GXRM 13 GFA kit with spiral hose and adjustable float;
- On a 12 V or 24 V battery: the 12/24 V lift pumps.
The whole range is in the cellar pumps category.
Frequently asked questions
What is the difference between a built-in float and an external float?
A built-in float is part of the pump: it is simple to set up. An external float is separate or mounted beside the pump and its type (vertical, cable) varies by model; some kits let you adjust it. The exact type is stated on each product page.
Which hose should I use with a cellar pump?
Choose a discharge hose with a diameter at least equal to the pump outlet, stated on the product page (for example 1" 1/4 on the Calpeda GXRM GFA). The longer, narrower or more twisted it is, the lower the flow. A reinforced flexible hose suits a mobile set-up.
What power or current should I allow for?
The current drawn is on each model’s page: for example 2.3 A, 3.2 A and 4.5 A for the 0.25, 0.37 and 0.45 kW ratings of the Calpeda GXRM GFA on 230 V single-phase. Check that the supply line can carry this current, with residual-current protection.
Can a cellar pump handle waste water?
No: it is made for clean or very slightly loaded water. For waste water with solids you need a suitable lift pump or a macerator pump. See the guide choosing a lift pump.
How much water is left on the floor after pumping?
It depends on the model. A floor-suction model pumps at low water level and leaves a film of a few millimetres; a standard cellar pump stops higher. The residual level is stated on the product page.
Why is my cellar pump not working?
First check the power supply (circuit breaker or residual-current device), then the float (free to move), the intake (blocked strainer or impeller) and the discharge hose (kinked or blocked). The details are in the section “My cellar pump will not start or has stopped pumping” above. Always unplug the pump before checking it.
What flow rate does a cellar pump have?
It is read in l/h or m³/h (1 m³/h = 1,000 l/h) and it falls as the discharge head rises. For example, the 0.25 kW Calpeda GXRM GFA gives a maximum of 10.2 m³/h at low head, for a maximum head of 9 m: read the flow at your own head on the manufacturer’s curve.
Cellar pump or lift pump: which one to choose?
To empty a cellar or garage of clean or slightly loaded water now and then, a cellar pump placed on the floor is enough. For permanent drainage or waste water, choose a lift pump.