Most household well pumps need between 500 and 2,000 watts to start, depending on the pump type and how deep your well is

The wattage your well pump requires falls into two numbers: starting watts (the surge of power needed when the motor first turns on) and running watts (the steady power it uses once it's operating). Starting watts are always higher—sometimes two to three times higher—because electric motors draw extra current at startup. A pump rated at 1,000 running watts might need 2,500 starting watts for the first second or two.

The actual wattage depends on three things: whether you have a submersible pump (sits inside the well) or a jet pump (sits above ground), how many gallons per minute it's designed to push, and how deep the water sits below the surface. A shallow-well jet pump for a 25-foot well might use 750 running watts. A deep-well submersible pump pulling water from 200 feet could need 1,500 running watts or more.

Key Takeaways

  • Check your pump's nameplate or manual for the exact running and starting wattage—this is the only reliable number for your specific model.
  • Starting watts are typically two to three times higher than running watts, so your backup power source or generator must handle the surge.
  • Jet pumps generally use 500 to 1,200 running watts; submersible pumps typically use 800 to 2,000 running watts depending on depth and flow rate.
  • If you're sizing a generator or battery backup, add 20 to 30 percent to the starting wattage to account for voltage drop and safety margin.

Finding the wattage on your pump

The most accurate way to know your pump's wattage is to look at the nameplate—a metal or plastic label attached to the motor itself. It lists running watts (sometimes called "rated watts" or shown as horsepower), starting watts (sometimes called "locked rotor amps" or "LRA"), and voltage. If you can't find the nameplate or it's worn away, check the pump's manual or contact the manufacturer with your pump model number.

If you don't have access to either, you can estimate based on horsepower. A 0.5 HP pump typically uses 400 to 600 running watts. A 1 HP pump uses 750 to 1,000 running watts. A 1.5 HP pump uses 1,100 to 1,500 running watts. A 2 HP pump uses 1,500 to 2,000 running watts. These are rough ranges—the actual number varies by motor efficiency and manufacturer. Always verify with the nameplate before making decisions about generators or backup power.

Why starting watts matter more than running watts

When you turn on your well pump, the motor doesn't when ready reach its normal operating speed. For the first second or two, it draws a massive current spike called inrush current. This is why a generator rated for 2,000 running watts might fail to start a pump that only needs 1,000 running watts—the generator can't handle the 2,500 starting watts the pump demands.

This matters most if you're running your pump on a generator, battery backup system, or solar inverter. A generator undersized for starting watts will either shut down when ready (many have automatic shutoff to protect themselves) or strain so hard that it damages the motor over time. When shopping for backup power, always match the starting wattage, not the running wattage. Once the pump is running, it will settle into its lower running-watt draw.

Jet pumps versus submersible pumps: wattage differences

Jet pumps sit above ground and pull water up from the well through a pipe. They're simpler and easier to service, but they can only pull water from about 25 feet deep (shallow-well models) or up to 100 feet with special equipment (deep-well models). A typical shallow-well jet pump uses 500 to 800 running watts. A deep-well jet pump uses 1,000 to 1,200 running watts because it has to work harder against the depth.

Submersible pumps hang inside the well on a cable and push water up rather than pulling it. They work at any depth and are more efficient, but they're harder to repair. A submersible pump for a 50-foot well might use 800 running watts. One for a 200-foot well could use 1,500 to 2,000 running watts. The deeper the pump sits, the more pressure it must overcome, and the more wattage it needs.

Calculating wattage for a generator or backup system

If you're buying a generator to run your well pump during an outage, don't just match the starting wattage. Add 20 to 30 percent as a safety margin to account for voltage drop in long extension cords and to protect the generator from running at absolute maximum capacity. A pump with 2,500 starting watts should be paired with a generator rated for at least 3,000 to 3,250 starting watts.

For battery backup systems or solar inverters, the math is the same. A 3,000-watt inverter can technically handle a pump with 2,500 starting watts, but it will be running at its limit. A 4,000-watt inverter gives you headroom and lets the system run more reliably. If your pump is 1.5 HP or larger, or if your well is very deep, consider a generator or inverter one size up from the minimum.

Common mistakes when estimating pump wattage

The biggest mistake is assuming running watts and starting watts are the same. They're not. A homeowner might see "1,000 watts" on a pump label and buy a 1,000-watt generator, then be shocked when the generator shuts down the moment the pump tries to start. Always read the nameplate carefully and look for both numbers.

Another common error is forgetting that other appliances might run at the same time. If you're on generator power during an outage and you want to run the well pump plus a refrigerator, a light, and a phone charger, you need enough wattage for all of them combined. The pump's starting surge happens first, but once it's running, you're drawing pump running watts plus whatever else is on. Plan for that total.

A third mistake is buying a generator based on horsepower alone without checking the actual wattage. A "1 HP pump" from one manufacturer might use 750 watts; another brand's 1 HP pump might use 1,000 watts. The horsepower rating is approximate. The nameplate wattage is exact.

What affects how many watts your pump uses

The depth of your well is the single biggest factor. Shallow wells (under 50 feet) need less power because the pump doesn't have to overcome as much pressure. Deep wells (150 feet or more) need significantly more wattage. If you've had your well drilled recently, your well report should list the static water level—how far down the water sits when the pump isn't running. That number tells you roughly how hard your pump has to work.

The flow rate also matters. A pump designed to deliver 5 gallons per minute uses less power than one designed for 15 gallons per minute. Larger households with higher water demand often have higher-flow pumps, which means higher wattage. The pump's age and condition matter too. An old, worn pump might draw more wattage than a new one of the same model because the motor is less efficient.

Frequently Asked Questions

Can I run my well pump on a standard household circuit?

Most well pumps need a dedicated circuit because their starting surge is too high for a shared circuit. A 15-amp household circuit can handle about 1,800 watts continuously, but a pump with 2,500 starting watts will trip the breaker. Well pumps should be on their own 20-amp or 30-amp circuit, depending on the pump's size. Check your pump's nameplate and have a licensed electrician verify your wiring.

What's the difference between running watts and starting watts?

Running watts is the steady power the pump uses once it's operating normally. Starting watts is the surge of power needed for the first second or two when the motor is accelerating from zero to full speed. Starting watts are typically two to three times higher. A generator or power system must handle the starting watts or it will shut down when you turn on the pump.

Do I need to know the wattage if I'm just replacing my pump with the same model?

Not necessarily, since your existing electrical setup already handles it. But if you're upgrading to a larger pump, switching from a jet pump to a submersible, or planning for a generator, you'll need the wattage of the new pump. Check the nameplate before you buy.

Why does my pump use more watts in summer than winter?

It usually doesn't, but it may seem to. In summer, you use more water (watering lawns, filling pools), so the pump runs more often and longer. The wattage per cycle stays the same. If your electric bill is higher, it's because the pump is running more hours, not because each cycle uses more power.

Can I use a smaller generator if I turn off other appliances when the pump starts?

Yes, but only if you time it carefully. If you turn off everything else and start only the pump, the generator only needs to handle the pump's starting watts. Once the pump is running, you can turn other things back on as long as the total doesn't exceed the generator's running-watt capacity. This works in an emergency, but it's inconvenient and risky if you forget to switch something off.