A typical sump pump draws about 1,000 watts while pumping (roughly 700 W for 1/3 HP to 1,300 W for 1/2 HP models). Starting surge is about 2,000-2,200 watts for a 1/2 HP pump.
- Running watts
- 1,000 WTypical; 700–1,300 W across models
- Starting watts
- 2,150 WGenerac's chart lists about 2,150 W to start a 1/2 HP sump pump; 1/3…
- Per day
- 1.2 kWh24 h of use, cycling
- Current
- 8.3 AAt 120 V while running
Figures checked against DOE, ENERGY STAR and manufacturer data on . Your model's label is the final word.
Watts by model and setting
Most sump pump models draw between 700 and 1,300 W while running; a typical one draws about 1,000 W. Highly weather-dependent: assumes the pump cycles about 5% of the time (roughly 70 minutes a day) during a wet period; 1,000 W x 24 h x 0.05 = 1.2 kWh. In dry weather it may barely run; in a storm it can run far more.
- Horsepower: 1/3 HP pumps draw less than 1/2 HP or 3/4 HP models
- Lift height and pipe run: pumping against more head changes the motor load
- Rainfall and water table set how often the float switch cycles the pump
- Cast-iron, permanent split capacitor motors and newer efficient designs draw less per gallon
Running a sump pump on a generator or power station
- Generator: at least 1,000 running watts and 3,150 starting watts (running plus the 2,150 W start surge, the cautious way to size it). Check both numbers on the spec sheet. A generator rated 3,500 W or more covers it with room to spare.
- Power station: continuous output of at least 1,000 W and a surge rating that covers about 2,150 W. Pure sine wave output is the safe choice for motors and electronics.
| Power station capacity | Estimated runtime |
|---|---|
| 500 Wh | 8.5 h |
| 1,000 Wh | 17 h |
| 2,000 Wh | 34 h |
| 3,000 Wh | 51 h |
Based on 50 W average draw (running watts × duty cycle) and 85% usable capacity.
- A sump pump is often the top-priority load in a storm outage; size for the starting surge (about 2,200 W for 1/2 HP), not just the running watts
- A power station needs a surge rating above the pump's start draw and enough battery for repeated cycles; a 1,000 Wh unit may cover only a few hours of heavy pumping
- Pure sine wave output is recommended for induction motors
- Run a gas generator outdoors only, at least 20 feet from doors, windows and vents; carbon monoxide from generators kills. Use heavy-duty extension cords or a professionally installed transfer switch, never backfeed a home outlet.
Add it to the generator calculator
Questions people ask
What size generator do I need for a sump pump?
A 1/2 HP sump pump runs on about 1,000-1,050 W but needs roughly 2,150 W to start, so a generator of at least 2,500-3,000 starting watts is a comfortable minimum. Add other loads you plan to run at the same time.
Can a portable power station run a sump pump?
Yes, if its surge rating covers the motor start (around 2,000 W for 1/2 HP) and it has pure sine wave output. Battery capacity limits runtime: each cycle uses only a little energy, but a pump cycling constantly in a storm can drain a 1-2 kWh station within hours.
How many amps does a 1/3 HP sump pump draw?
Manufacturer specs for common 1/3 HP cast-iron pumps list a maximum of about 9-10 amps at 115 V; actual draw while pumping is usually somewhat lower.