Power depends on horsepower and head pressure
A typical 1/3 HP residential sump pump draws 800 to 1,000 watts while running. A 1/2 HP model draws 1,000 to 1,200 watts. The pump only runs when the float switch activates, which depends on groundwater level, rainfall, and the pump's basin size.
During a dry week the pump may not run at all. During a heavy storm it could cycle every few minutes. Annual energy use is highly variable and site-specific.
Estimate for a wet season
If a 1,000-watt pump runs for 5 minutes every 30 minutes during a 12-hour storm, that is 12 cycles × 5 minutes = 60 minutes of runtime, or 1 kWh for that storm. Over a wet month with 8 such events, that adds about 8 kWh, or roughly $1.50 at 18 cents per kWh.
Backup battery pumps (common for power outages) draw additional charging power, typically 50 to 100 watts continuously, adding 1.2 to 2.4 kWh per day regardless of pumping.
- Test the pump monthly by pouring water into the basin to verify the float switch.
- Keep the intake screen clear of debris to prevent motor overload.
- Consider a water-powered backup pump if power outages are frequent.
Cost is small but reliability matters more
Even in a very wet season, a sump pump's electricity cost is usually under $10 per month. The real cost of failure is basement flooding. Prioritize a quality pump, proper installation, and a reliable backup over optimizing the electric bill.
Rate source and limits
The default rate is the EIA U.S. residential average for April 2026, retrieved July 16, 2026. It is an average revenue per kilowatt-hour, not a quote for your utility plan. Fixed fees, taxes, tiers, and time-of-use prices can change the bill.
Open the EIA source