Most household well pumps need between 750 and 2,200 watts to start, depending on the pump type and depth of your well

The wattage your well pump requires falls into two categories: running watts (what the pump uses once it is moving water) and starting watts (the surge of power needed at the moment you turn it on). Starting watts are almost always higher — sometimes double the running figure — because electric motors demand extra current to overcome initial resistance and get the pump spinning.

A shallow-well jet pump typically needs 750 to 1,500 starting watts. A submersible pump for a deeper well usually needs 1,500 to 2,200 starting watts. If your well is very deep or your pump is oversized for the job, you may see requirements above 2,200 watts. The only way to know your pump's exact requirement is to check the nameplate on the motor itself or your pump's manual — the label will list both running and starting watts.

This matters because if your backup power source (a generator, for example) cannot deliver the starting watts, the pump will not turn on, even if it could easily handle the running load. A generator rated for 5,000 watts running capacity might only produce 6,000 watts at startup — enough to start your pump — but a 3,000-watt generator would fail.

Key Takeaways

  • Starting watts are the critical number: your power source must deliver them at the moment the pump turns on, or the pump will not run.
  • Shallow-well jet pumps typically need 750 to 1,500 starting watts; submersible pumps for deeper wells need 1,500 to 2,200 starting watts.
  • The motor nameplate on your pump lists both running and starting watts — this is the only reliable source for your specific pump.
  • A generator or backup power system must be rated for starting watts, not just running watts, or it will fail to start the pump.
  • Older pumps and oversized pumps may require more wattage than newer, properly sized models.

Why Starting Watts Matter More Than Running Watts

Once your pump is running, it draws its rated running watts — typically 500 to 1,500 watts for a household pump. But at the when ready you flip the switch, the motor needs a temporary surge to overcome static friction and magnetic resistance in the motor windings. This surge can be 2 to 3 times the running wattage and lasts only a few seconds.

If your power source cannot deliver that surge, the motor will hum or click but not spin. The pump sits idle while drawing current, which can damage the motor over time. This is why a generator that seems powerful enough on paper often fails to start a well pump in practice — the manufacturer rated it for continuous running watts, not the brief but intense starting demand.

For this reason, always size your generator or backup power system to the starting watts, not the running watts. A 5,000-watt generator is a safer choice than a 3,500-watt one if your pump needs 2,200 starting watts, even though the pump will only draw 1,000 watts once it is moving.

How Pump Type Affects Wattage Requirements

Jet pumps (the most common type for shallow wells under 25 feet) are relatively efficient and need less power. A typical 1-horsepower jet pump draws 750 to 1,200 starting watts. If your well is shallow and your household is small, a jet pump may be all you need.

Submersible pumps sit at the bottom of the well and push water up through a pipe. They are standard for deeper wells and typically need 1,500 to 2,200 starting watts for a 1-horsepower model. Larger homes with higher water demand often use 1.5-horsepower or 2-horsepower submersible pumps, which can require 2,500 to 3,500 starting watts.

Variable-speed pumps are newer and more efficient. They ramp up gradually instead of starting at full power, which reduces the starting surge. A variable-speed pump may need only 1,200 to 1,800 starting watts even at 1.5 horsepower. If you are planning a new installation or replacing an old pump, a variable-speed model will lower your power requirements and reduce your electricity bill.

How Well Depth and Water Demand Change the Load

A deeper well requires more power because the pump must push water a greater distance. A well at 50 feet demands more wattage than one at 20 feet, all else equal. Similarly, a household that uses more water — multiple bathrooms, a large family, livestock — needs a pump that runs longer and harder, which means higher wattage.

If your well is 200 feet deep and you have a 4-bedroom house with two bathrooms, you may need a 2-horsepower submersible pump rated for 3,000 starting watts. The same pump in a shallow 30-foot well serving a small cabin would be overkill and waste energy. A well contractor can assess your well depth and household water use and recommend the right pump size — which directly determines the wattage you need.

Oversizing a pump is common and costly. A pump larger than necessary will cycle on and off more frequently, wear out faster, and draw more power than required. If you are replacing a pump, use the same horsepower as the original unless a contractor tells you the old pump was undersized.

Finding Your Pump's Wattage Rating

The most reliable source is the motor nameplate, a metal or plastic label attached to the pump motor itself. It lists the horsepower, voltage, amperage, and often the starting and running watts directly. If the label is missing or illegible, check your pump's manual or the paperwork from installation.

If you do not have the manual, you can calculate running watts using the formula: volts × amps = watts. A 240-volt pump drawing 6 amps uses 1,440 running watts. To estimate starting watts, multiply the running watts by 2 to 3, depending on the motor type. This is an estimate, not a may provide, so err on the side of a larger power source.

If you cannot find the nameplate and do not know the pump's age or model, contact a local well contractor or pump supplier with your well depth and household size. They can tell you what pump is likely in your well and what wattage it needs. Some contractors will visit your home and read the nameplate for a small fee.

Choosing a Generator or Backup Power System

If you need a generator to run your well pump during a power outage, buy one rated for at least the starting watts your pump requires — ideally 20 to 30 percent higher to account for other loads (lights, refrigerator, etc.). A pump needing 2,200 starting watts should pair with a 5,000 to 6,000-watt generator, not a 3,500-watt one.

Portable generators are cheaper but noisier and require manual setup. Standby generators are permanently installed, run on natural gas or propane, and start automatically when power fails. Both types must be sized to your pump's starting watts. A standby generator rated for 7,500 watts running capacity will have a higher starting capacity and is a safer choice for a 2,200-watt pump than a portable generator of the same running rating.

If you are installing a solar power system or battery backup, the same rule applies: the inverter (the device that converts DC power to AC) must be rated for your pump's starting watts, not just running watts. A 3,000-watt inverter will not start a 2,200-watt pump reliably.

Common Mistakes That Waste Power or Cause Failure

Buying a generator or power system rated only for running watts is the most common mistake. A 3,000-watt generator sounds powerful, but if your pump needs 2,200 starting watts, it will not work. Always check the starting watts first.

Oversizing the pump is the second mistake. A 2-horsepower pump in a small household wastes electricity and wears out faster than a properly sized 1-horsepower pump. If you are replacing a pump, match the original horsepower unless a contractor recommends otherwise.

Ignoring the age of the pump is a third issue. Older pumps (more than 15 years) often draw more current than newer models of the same horsepower because the motor is less efficient. If your pump is old and your generator barely starts it, replacing the pump with a modern, efficient model may solve the problem and lower your power bill.

Frequently Asked Questions

Can I run my well pump on a 2,000-watt generator if the pump is rated for 2,200 starting watts?

No. The generator will not deliver enough power at startup, and the pump will not turn on. You need a generator rated for at least 2,200 starting watts, ideally 2,500 or higher to account for voltage drop and other loads. Undersizing the generator is a common reason backup power systems fail when you need them most.

What is the difference between a 1-horsepower and a 1.5-horsepower pump?

A 1.5-horsepower pump moves more water per minute and can handle deeper wells or higher demand. It also draws more wattage — typically 1,500 to 2,200 starting watts versus 750 to 1,500 for a 1-horsepower pump. Use the horsepower your well requires, not the largest available, to avoid wasting power.

Does a variable-speed pump really use less power?

Yes, in two ways. Variable-speed pumps have lower starting watts because they ramp up gradually instead of surging to full power when ready. They also use less running power because they adjust speed to match your water demand instead of running at full capacity all the time. The trade-off is higher upfront cost, but the electricity savings often pay for the difference over 5 to 10 years.

How do I know if my pump is oversized?

An oversized pump cycles on and off frequently (every few minutes) instead of running for 10 to 20 minutes at a time. It also draws more power than necessary and wears out faster. A well contractor can tell you if your pump is the right size for your well depth and household water use. If it is oversized, replacing it with a properly sized pump will lower your power bill and extend the pump's life.

Can I use a solar inverter to run my well pump?

Yes, if the inverter is rated for your pump's starting watts. A 3,000-watt inverter will not reliably start a 2,200-watt pump. You need an inverter rated for at least 2,500 to 3,000 starting watts, plus a battery bank large enough to supply the running watts for the time you expect to pump. Solar systems for well pumps are more complex and expensive than grid power, but they work if sized correctly.