How Much Does It Cost to Run a Sump Pump?
About $1.92 a month — $23.36 a year — for a common 1/3 HP pump drawing 800 watts and pumping 30 minutes a day at $0.16/kWh. The motor is large, but it is switched on 2.1% of the time, and that is the whole answer. Set your own pump and run time below.
Pump size
Horsepower sets both the watts and the flow. A bigger pump costs more per hour and finishes sooner, so the price of emptying the pit barely changes.
Typical for 1/3 HP: 600–1000 W. Use the nameplate on the pump, or amps × volts, if you have it.
Off the pump curve. Only affects the water figures below, not the bill.
An hour of pumping costs $0.13 at this rate.
30 minutes a day · 0.50 h · 2.1% duty cycle
Minutes, not hours — a pump that keeps up with the water it is given runs for a few of them a day. Drag the slider to the far end and you are pricing a stuck float switch, not a sump pump.
Cost to run this sump pump
$1.92 a month
$23.36 a year — 30 minutes of pumping a day at $0.13 an hour, which is 6.4¢ a day and 146 kWh over twelve months.
Water removed
383,250 gal
a year, at 35 GPM — 1,050 gallons a day
Price of that water
6.1¢
per 1,000 gallons lifted out of the pit
Wire-to-water efficiency
8.2%
of the wattage becomes lift at 10 ft; the rest is heat and noise
0.80 kW × 0.50 hours = 0.400 kWh a day × $0.16 = 6.4¢. Switch to a bigger pump and both the wattage and the gallons per minute go up together, so the price per 1,000 gallons hardly moves. What you buy with horsepower is a shorter run, not a cheaper one.
Work out your real run time by counting cycles
8 min a day · $0.51 a month
Stand by the pit during the rain, count how often it fires in an hour, and time one cycle on a phone. 4 cycles an hour × 20 seconds is 80 seconds of motor per hour, and over 6 hours of the day that is 8 minutes. This is worth doing once: it is the difference between a number that is yours and a number that is ours.
What a battery backup adds to the bill
Charger, per year
$7.01 · 44 kWh
The charger draws 5 W for all 8,760 hours of the year, rain or shine, which is 44 kWh and $7.01. The backup pump itself costs about 8.0¢ a year, because it only runs during a power cut — even after charging it at the wall, through a charger and battery that give back roughly 72% of what they take. At 30 minutes a day, your primary pump costs $23.36 a year, so the charger is 30% on top of it. The two draws are equal at 9 minutes of pumping a day.
Cost is running watts × hours × your rate; monthly figures use a 30-day month and annual ones 365 days. Wattage and flow presets are typical of the nameplates in each horsepower class, not measurements — read your own pump's label and curve and overwrite them. Wire-to-water efficiency compares the wattage against the exact hydraulic work of lifting that flow 10 ft. The model ignores the motor's starting surge, which lasts a fraction of a second but repeats on every cycle, so very short cycles cost slightly more than shown. Backup figures assume a 180 W DC pump running 2 hours a year at 72% round-trip efficiency. Not sure of your electricity rate? Check average rates by state.
Average sump pump wattage
Monthly cost = watts ÷ 1,000 × hours a day × your rate × 30
Horsepower is what the motor delivers to the impeller, not what it takes from the wall. A 1/3 HP rating is 249 watts of shaft power — a third of 746 — and a wet-rotor motor that small needs about 800 watts of electricity to produce it. That gap is normal, and it is why the nameplate on your pump is the only wattage worth trusting.
Worked example (800 W, 30 minutes a day, $0.16/kWh): 800 ÷ 1,000 = 0.8 kW × 0.50 hours = 0.4 kWh a day × $0.16 = $0.064 a day, which is $1.92 per month and $23.36 a year.
Typical wattage, flow and cost by pump size
The last column is the one to read. Wattage climbs 3-fold across this table, and the cost of lifting a thousand gallons hardly moves — because the bigger pump moves more water for those watts and shuts off sooner.
| Pump size | Running watts | Cost per hour | Flow at 10 ft | Per 1,000 gallons |
|---|---|---|---|---|
| 1/4 HP | 500 W400–650 W | $0.08 | 25 GPM | 5.3¢ |
| 1/3 HPThe common residential size | 800 W600–1000 W | $0.13 | 35 GPM | 6.1¢ |
| 1/2 HP | 1050 W800–1300 W | $0.17 | 45 GPM | 6.2¢ |
| 3/4 HP | 1300 W1000–1600 W | $0.21 | 55 GPM | 6.3¢ |
| 1 HP | 1600 W1200–2000 W | $0.26 | 65 GPM | 6.6¢ |
Wattage and flow are typical of the nameplates in each class, not measurements of any particular pump — read your own label and pump curve. Costs use $0.16/kWh; find yours on the rates by state page. Running watts exclude the starting surge, which is several times larger and lasts a fraction of a second.
Where the 800 watts actually go
Lifting 35 gallons a minute 10 feet is 66 watts of physical work — flow × head × 746 ÷ 3,960, the pump industry's own formula. The pump draws 800. So about 8% of what you pay for becomes lift, and the rest leaves as heat and noise. That is not a scandal, it is a design choice: a sump pump spends its life doing nothing, so nobody pays extra for the copper that would make the few minutes it works efficient. It is also why the total is so small — 8% of almost no runtime is still almost nothing. Even at this efficiency, 30 minutes a day lifts 383,250 gallons out of the basement over a year for $23.36 — about 6.1¢ per thousand gallons.
Continuous vs. intermittent run cost
A sump pump has no schedule. It runs when groundwater arrives and stops when the pit is empty, so its cost swings by a factor of hundreds between a dry week and a stuck float. Every row below is the same 800 W pump at $0.16/kWh; only the minutes change.
| Run time | Duty cycle | Water a day | Per month | Per year |
|---|---|---|---|---|
| Dry spell3 min a day · A couple of short cycles a day | 0.2% | 105 gal | $0.19 | $2.34 |
| Ordinary week15 min a day · Groundwater, no weather to speak of | 1.0% | 525 gal | $0.96 | $11.68 |
| Damp season30 min a day · This page's anchor figure | 2.1% | 1,050 gal | $1.92 | $23.36 |
| Wet spring120 min a day · Cycling steadily through a rainy month | 8.3% | 4,200 gal | $7.68 | $93.44 |
| Storm day480 min a day · A third of the day spent pumping | 33.3% | 16,800 gal | $30.72 | $373.76 |
| Continuous1440 min a day · Never shuts off — something is wrong | 100.0% | 50,400 gal | $92.16 | $1121.28 |
Water a day assumes 35 GPM. A 30-day month and a 365-day year. The bottom row is not a usage pattern — it is a fault, and the money is the least of it.
A pump that runs continuously is a fault, not a bill
Twenty-four hours a day of pumping is $92.16 a month, about 48 times normal. Before you price that, check why. Either the pit refills as fast as it empties — a water table problem, or a discharge line freezing or dumping too close to the house — or the float switch is stuck on and the pump is churning air. The second is common, and running dry destroys the motor far faster than the electricity costs you. Unplug it and free the float.
Short cycling makes you pay for the same water twice
When the motor stops, the water standing in the vertical discharge pipe wants to fall back into the pit. A check valve is what stops it. Without one, or with a failed one, a 8-foot rise of 1.5-inch pipe drops 0.73 gallons straight back down — 1.5-inch pipe holds 0.092 gallons a foot, 1.25-inch holds 0.064. Against a pit that draws down 5 gallons a cycle that is 15% more water through the impeller on every single cycle, and often enough to trip the float again immediately. The wasted electricity is pennies. The wasted motor starts are what you actually lose — starting is the hardest thing a pump motor ever does.
Count cycles, do not guess hours
Nobody knows their sump pump's hours per day, which makes the slider above a guess unless you feed it something real. You can get something real in ten minutes: stand by the pit in the rain, count the cycles in an hour, and time one on your phone. Four cycles an hour at twenty seconds each is eighty seconds of motor an hour — over six wet hours, eight minutes of running. The calculator will turn that into a month and a year for you.
Battery backup vs. AC-powered cost
A battery backup system has two electrical costs, and they are nothing like each other. The DC pump draws from a battery, and it only runs when the power is out — so it costs almost nothing. The charger that keeps that battery ready draws a few watts every hour of every day of the year, whether or not it ever rains.
| What is drawing power | Draw | Hours a year | kWh a year | Cost a year |
|---|---|---|---|---|
| AC primary pumpPumping, 30 minutes a day | 800 W | 183 | 146 | $23.36 |
| Backup battery chargerFloating, every hour of the year | 5 W | 8,760 | 44 | $7.01 |
| Backup DC pumpOnly during a power cut | 180 W | 2 | 0.5 | $0.08 |
The DC pump's energy is charged at the wall, not at the battery: a charger and a lead-acid battery give back roughly 72% of what they take, so a kilowatt-hour at the impeller costs more than one at the meter. Charger draw, backup pump size and outage hours are assumptions of this model — the first is the only one that matters, and manufacturers rarely publish it.
Primary pump, per year
$23.36
Its backup charger, per year
$7.01
Break-even run time
9 min
The charger is 30% on top of the pump it protects, and the two draws are exactly equal when the primary pump runs 9 minutes a day — 5 W across 24 hours is the same energy as 800 W across 9 minutes. If your basement is drier than that, the backup system uses more electricity than the pump it exists to back up. None of which is an argument against owning one: this is a machine bought for the night the power fails during a storm, and $7.01 a year of standby draw is a cheap insurance premium against a flooded basement. It is simply worth knowing which half of the system is on your bill.
Water-powered backup pumps are the other option, and they do not appear in this table because they use no electricity at all. They run on municipal water pressure, driving a venturi that pulls water from the pit — so they trade a kilowatt-hour bill for a water bill, and they need city water pressure that a well cannot supply.
Related Guides
Cost to Run a Dehumidifier
The other basement appliance — and the one that actually costs money
Vampire Appliances
Standby draws like the backup charger, adding up all year
Running Appliances 24/7
What continuous operation costs, when it is not a stuck float
Electricity Rates by State
The rate every figure on this page depends on
Compare Appliance Costs
See how a sump pump stacks up against everything else you run
How to Save on Energy Bills
Practical tips by room with savings
Frequently Asked Questions
How much does it cost to run a sump pump?
About $1.92 a month, or $23.36 a year, for a 1/3 HP pump drawing 800 watts and pumping for 30 minutes a day at the US average $0.16/kWh. That is 146 kWh a year — less than most refrigerators use in three months. A sump pump has a big motor and a tiny duty cycle: at 30 minutes a day it is energised 2.1% of the time. The wattage frightens people; the hours are what they should be looking at.
How many watts does a sump pump use?
Residential pumps run from about 400 watts for a 1/4 HP up to roughly 2000 watts for a 1 HP, with 1/3 HP — around 800 watts — the size most pits are fitted with. Horsepower describes what the motor delivers to the impeller, not what it draws from the wall: 1/3 HP is 249 watts of shaft power, and a wet-rotor motor that small takes several times that to produce it. Read the nameplate on your own pump rather than trusting a table, including ours. The motor also draws a starting surge many times its running watts for a fraction of a second on every cycle, which no wattage table shows.
How much does it cost if my sump pump runs constantly?
A 800-watt pump running all 24 hours costs about $92.16 a month and $1121 a year at $0.16/kWh — roughly 48 times the normal bill. But the bill is not the problem. A pump that never stops is either sitting in a pit that fills as fast as it empties, or its float switch is stuck on and it is pumping air. The second is common, and it burns out the motor. If your pump is running continuously and the pit is not full, unplug it and free the float before you think about the electricity.
Does a battery backup sump pump use electricity when it is not pumping?
Yes, and that is nearly all it ever uses. The charger that keeps the battery topped up draws a few watts continuously — 5 W is typical — for all 8,760 hours of the year, which is 44 kWh and about $7.01. The backup pump itself costs pennies, because it only runs during a power cut. Against a primary pump that costs $23.36 a year, the charger adds 30%. Below 9 minutes of pumping a day, the charger costs more to run than the pump it is backing up. It is still worth having — a flooded basement costs more than a lifetime of trickle charge.
Does a bigger sump pump cost more to run?
Per hour, yes. Per basement, barely. A bigger pump draws more watts and moves proportionally more water, so it empties the pit sooner and shuts off sooner. Across the whole 3-to-one range of wattage on this page, the cost of lifting 1,000 gallons only moves from 5.3¢ to 6.6¢. Your electricity bill is set by how much groundwater arrives, not by the pump you bought. Size the pump to the water your pit takes on, not to the meter.
Why does a short-cycling sump pump cost more?
Because you pay to pump the same water twice. When the check valve is missing or has failed, the column of water standing in the vertical discharge pipe drops back into the pit the moment the motor stops. A 8-foot rise of 1.5-inch pipe holds 0.73 gallons; against a pit that draws down 5 gallons a cycle, that is 15% more water through the impeller, every cycle, forever. The extra dollars are trivial. The extra motor starts are not — starting is the hardest thing a pump motor does, and a check valve costs less than a call-out.