Most residential well pumps draw between 750 and 2,200 watts while running
The wattage your well pump uses depends on its horsepower, the depth of your well, and how hard the pump has to work to push water to your house. A typical 1-horsepower (HP) submersible pump draws roughly 750 to 1,000 watts during operation. A 1.5 HP pump uses around 1,100 to 1,500 watts. A 2 HP pump draws 1,500 to 2,200 watts. These are running watts—the power the pump uses while it is actively moving water.
The number that matters most for your electrical system is starting watts, not running watts. When a well pump first turns on, it draws a surge of power that can be two to three times higher than its running wattage. A 1 HP pump might need 2,000 to 3,000 watts just to start. This surge lasts only a few seconds, but your electrical panel and any backup generator must be sized to handle it, or the pump will not start at all.
Key Takeaways
- A 1 HP well pump uses 750 to 1,000 running watts; a 2 HP pump uses 1,500 to 2,200 running watts.
- Starting watts are two to three times higher than running watts, so a 1 HP pump may need 2,000 to 3,000 watts to turn on.
- Your electrical panel must be sized for the starting wattage, not the running wattage, or the pump will not start.
- If you are planning a backup generator, size it for at least the starting watts of your pump plus any other loads you want to run simultaneously.
How to find your pump's actual wattage
The most reliable way to know your pump's wattage is to look at the nameplate on the pump itself or in your well system documentation. The nameplate lists the horsepower, voltage (usually 230 volts for residential wells), and sometimes the amperage. If you see amperage listed, you can calculate watts by multiplying volts × amps. For example, a pump running at 230 volts and drawing 5 amps uses 1,150 watts.
If you cannot find the nameplate or documentation, you can estimate based on horsepower. Divide the horsepower by 0.75 to get a rough running wattage. A 1 HP pump ÷ 0.75 = roughly 1,333 watts, though real-world usage is usually lower (750 to 1,000 watts) because the pump does not run at full load all the time. For starting watts, multiply the running watts by 2.5.
If you want to measure your pump's actual power draw, you can hire an electrician to use a clamp meter on the wire feeding the pump. This takes about an hour and costs $100 to $200, but it gives you the exact number for planning a generator or upgrading your electrical service.
Why starting watts matter more than running watts
When a motor first starts, it draws a large inrush current because the motor windings have zero resistance at the moment of startup. As the motor spins up, resistance increases and current drops to its normal running level. This is why a 1 HP pump might draw 750 watts while running but need 2,000 watts to start.
If your electrical panel is undersized or your generator is too small, the voltage will sag when the pump tries to start. The pump motor will not have enough power to overcome the friction in the well and begin turning. You will hear a humming sound from the pump but the impeller will not spin. The motor will overheat and eventually burn out if it keeps trying to start without enough power.
This is also why you cannot straightforward add up the running watts of all your household devices and assume that is your panel capacity. Your panel must handle the largest single starting surge—usually the well pump or air conditioner—plus whatever else is running at that moment.
Sizing a backup generator for your well pump
If you want a generator to keep your well running during a power outage, size it for at least the starting watts of your pump. A 1 HP pump needs a generator rated for at least 5,000 to 7,000 watts (5 to 7 kW). A 2 HP pump needs 8,000 to 10,000 watts (8 to 10 kW). These numbers give you a safety margin so the generator does not strain when the pump starts.
If you also want to run other loads—lights, a refrigerator, a sump pump—add their running watts to the pump's starting watts. A refrigerator uses about 600 to 800 running watts. A sump pump uses 500 to 1,000 running watts. So a 1 HP well pump (2,500 starting watts) plus a refrigerator (700 running watts) plus a sump pump (800 running watts) would need a generator rated for at least 4,000 watts.
Portable generators are usually rated in running watts on the label, so look for the "starting watts" or "surge watts" specification. If the label does not list starting watts, assume they are about 1.5 times the running watts. Permanently installed standby generators are usually sized by an electrician based on your home's total load.
What affects how many watts your pump actually uses
The depth of your well is the biggest factor. A shallow well (under 25 feet) requires less power because the pump does not have to push water as far. A deep well (100+ feet) requires significantly more power. If your well is 300 feet deep, your pump may be a 2 HP model instead of 1 HP, doubling the wattage.
The diameter and length of your water line also matter. A long run of small-diameter pipe creates friction that makes the pump work harder. If your house is 500 feet from the well, the pump uses more watts than if it were 50 feet away. The pressure tank size and the water pressure setting (usually 40 to 60 PSI) also affect how often the pump runs and for how long, which changes your average power consumption over time.
Age and condition of the pump matter too. An old pump with worn impellers or bearings may draw more watts than a new one of the same horsepower because it has to work harder to move the same amount of water. If your pump is more than 15 years old and your electric bill has been climbing, the pump may be losing efficiency.
When to call an electrician about your pump's power draw
Call an electrician if your pump hums but does not start, or if it starts and stops repeatedly without building pressure. These are signs the electrical service to the pump is undersized or the breaker is too small. The electrician can measure the actual amperage draw and determine whether the problem is the pump, the wiring, or the panel.
Also call an electrician if you are installing a backup generator and want to know whether your panel can handle the generator's output. The electrician will size the transfer switch and any new circuits based on your pump's starting watts and your other loads.
If you are planning to upgrade your well pump to a larger horsepower (for example, if you are adding a second bathroom), ask the electrician whether your current electrical service can handle it. A jump from 1 HP to 2 HP may require upgrading the breaker, the wire gauge, or even the main service panel.
Frequently Asked Questions
Can I run my well pump on a portable generator?
Yes, if the generator is large enough. A 1 HP pump needs at least a 5,000 to 7,000 watt generator. Plug the pump directly into the generator using a heavy-duty extension cord rated for the amperage, or have an electrician install a manual transfer switch so you can switch between grid power and generator power without unplugging anything.
Why does my electric bill spike when the well pump runs?
The pump uses a lot of power, but only while it is actively pumping. If your bill is unusually high, the pump may be running constantly because of a leak in the pressure tank, a broken check valve, or a drop in water level. An electrician or well technician can diagnose the problem.
What is the difference between a 1 HP and a 2 HP well pump?
A 2 HP pump moves more water per minute and can reach deeper wells. It also uses roughly twice the wattage (1,500 to 2,200 watts running, 4,000 to 5,000 watts starting). Choose based on your well depth, household water demand, and whether your electrical service can handle the larger starting surge.
Do I need to upgrade my electrical panel for a new well pump?
Only if your current panel does not have a breaker large enough for the pump's amperage, or if the main service is undersized. An electrician can check this by looking at your panel and the pump's nameplate. Many homes can accommodate a 1 or 1.5 HP pump without upgrades, but a 2 HP pump or larger may require a new breaker or service upgrade.
How much does it cost to run a well pump for a year?
This depends on your electricity rate, how often the pump runs, and the pump's horsepower. A 1 HP pump running 8 hours per day at an average rate of $0.12 per kilowatt-hour costs roughly $200 to $300 per year. A 2 HP pump costs roughly $400 to $600 per year under the same conditions. These are estimates; your actual cost varies by region and usage.