3,500 running watts starts any residential sump pump with room for the fridge and lights, dual fuel keeps it fed during long storms, and it's the least money that does the whole job.
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~$549 typical price
Buy on AmazonUse-case guide · 2026
Best generator for a Sump Pump
Sump pumps have the cruelest failure mode in the house: the same storm that floods your basement is the one that kills the power. A generator (or battery backup) for the sump pump routinely pays for itself in one avoided insurance claim.
The power requirements
Running watts
800W (⅓ HP) to 1,050W (½ HP)
Starting surge
1,300–2,200W depending on horsepower
- ▸Starting surge is the number that matters — a ½ HP pump can briefly demand over 2,000W.
- ▸During active flooding a pump may cycle every minute or two, so fuel/battery consumption is much higher than for a fridge.
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Our picks
2. EcoFlow DELTA Pro
9.0
/ 10
Plug the pump into the DELTA Pro with pass-through power and it functions as a giant UPS: the instant utility power drops, the pump keeps running on battery with zero action from you — crucial if the outage starts while you're asleep or away.
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~$2,699 typical price
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3. Westinghouse iGen4500
9.1
/ 10
Handles the pump plus household essentials at conversation volume, with eco-mode runtimes that cover an all-night storm on one tank.
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~$949 typical price
Buy on AmazonBefore you buy
- ▸The battery-as-UPS setup is the only option that works when nobody's home — a generator can't start itself.
- ▸Check your pump's HP rating on the housing; ⅓ HP vs ½ HP changes the surge math.
- ▸A water-powered backup sump pump (no electricity at all) is a smart belt-and-suspenders addition if you have municipal water.
Frequently asked questions
Will a battery station keep a sump pump running automatically?
Yes — plug the pump into a station that supports pass-through/UPS operation and it switches to battery instantly when the grid drops. A 2–3.6kWh unit typically covers several hours of heavy pumping; pair with a generator for multi-day storms.
What size generator do I need for a ½ HP sump pump?
At least 2,200W peak capacity for the pump alone; a 3,000–4,500W class unit is the practical choice so the fridge and lights can run alongside it.