What Size Generator for Sump Pump?
Sump pumps are critical during storms - exactly when power outages happen. A 2000W generator handles most sump pumps with room for other essentials. Battery backup sump pumps provide automatic protection.
Minimum Size
1500W
bare minimum, tight
Comfortable Size
2000W
recommended
Ideal Size
3000W
room to grow
Total Running Watts
500W
Total Surge/Starting Watts
1500W
Generator Sizing Calculator
Additional Custom Load
Running Watts
1550W
Surge Watts
4650W
Recommended Generator
6000W+
Includes 25% headroom for reliable operation
Suitable Generator Sizes
Estimated Fuel Usage
* Fuel estimates are approximate. Actual consumption varies by generator model, load, and altitude.
Typical Loads for Sump Pump
| Item | Running Watts | Surge Watts |
|---|---|---|
| 1/3 HP Sump Pump | 350W | 1050W |
| 1/2 HP Sump Pump | 500W | 1500W |
| 3/4 HP Sump Pump | 700W | 2100W |
| Total | 500W | 1500W |
* Surge watts apply to motor loads during startup. Size your generator for worst-case surge scenario.
Generator Sizing Tips
- •Battery backup sump pumps work automatically during outages
- •Test your backup system before storm season
- •Sump pumps only run intermittently, not continuously
- •A 2000W generator can run sump pump + fridge + lights
- •Keep generator fuel fresh - storms often follow long storage periods
Key Considerations
- ⚠Storms cause outages when you need sump pump most
- ⚠Battery backup is automatic, generator requires manual start
- ⚠Keep discharge line clear of debris and ice
Alternatives to Consider
- ✓12V battery backup sump pump (automatic)
- ✓Water-powered backup sump pump
- ✓Portable power station for short outages
Frequently Asked Questions
What size generator for a sump pump?
A 2000W generator handles most residential sump pumps (up to 1/2 HP). The 1500W surge of a 1/2 HP pump fits within a 2000W generator's surge capacity.
How long can a generator run a sump pump?
Indefinitely, as long as you have fuel. A sump pump only runs 5-10 minutes per cycle, so actual power consumption is low. A 3-gallon tank could last 10+ hours of storm drainage.
Should I get a battery backup or generator for sump pump?
Both ideally. Battery backup (12V DC pump) is automatic and silent. Generator handles longer outages and can power other things. For basement protection, a battery backup is essential.