How Many Watts Does A Well Pump Use? (Find Out Now!)

Patricia Oelze
by Patricia Oelze

If you get your water from a well, you probably already know that when your power goes out, your water does not work either. As if it isn’t bad enough to have no electricity, now you have no water either. You should consider getting a generator for the well pump then.

A 1 HP submersible well pump needs a 2.5 KW generator to operate the pump. A 30 amp breaker with a pump smaller than 2 hp will use 11 amps or 2000 watts during operation. Additionally, it will need a 4 KW internally regulated generator for the pump to operate efficiently. A typical 3-4 bedroom home requires an 8-12 GPM well pump, consuming 750 running watts and 2,000 starting watts.

However, there is more to it than just the wattage to run the pump. A generator has a starting watt power as well as a running watt power. To find how many watts you need to start your well, you have to use a number that is double to triple the running wattage.

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Different Sizes of Well Pumps and Wattages

Pumps can be larger than that as well. A ¾ horsepower well uses 1,500 to 1,800 watts to run and needs. In fact, a large well for a whole community can be as large as 10 horsepower, using about 15,000+ watts to run and at least 30,000 watts to start.

To determine your well pump’s wattage, you have to know the horsepower. And to know the horsepower, you have to know the size of the well pump. All this is determined by how much water is needed. But there are many different sizes of pumps depending on what size household or community is using the well.

Size of Pump MotorRunning WattageStarting Wattage
1/3 HP750 to 8001,500 to 2,400
1/2 HP900 to 1,0501,800 to 3,150
3/4 HP1,500 to 1,8003,000 to 5,400
1 HP2,000 to 2,4004,000 to 7,200
1.5 HP2,500 to 2,8005,000 to 8,400
2 HP3,750 to 4,0007,500 to 12,000
3 HP5,000 to 5,50010,000 to 16,500
5 HP7,500 to 8,00015,000 to 24,000
7.5 HP10,000 to 11,00020,000 to 33,000
10 HP15,000 to 16,00030,000 to 48,000

Four Different Types of Pumps

There are four different types of well pumps that are most commonly used. These include the submersible pump, jet pump, turbine pump, and cylinder pump.

Submersible Pump

The most common type of well pump, the submersible pump is comprised of a pump and a motor that is usually about two or three feet long and 3.5 inches in diameter. This pump sits in the well below the water level. They are most often used in wells that are over three inches in diameter.

Video: How To Run A Submersible Well Pump Off A Portable Generator

Jet Pump

If your well is less than 3.5 inches in diameter such as a shallow drive-point well, the pump used may be a jet pump. These are found on top of the well or set off to the side in a pump house. It is attached to the well through pipes.

The jet pump uses a lower water yield and lower operating pressure than a submersible pump. The way they work is by pushing water through a narrow cone-shaped device called a jet. This creates a suction that draws water from the well.

The jet pump may be a shallow well pump or deep well pump. The shallow well type is used for water that is less than 25 feet below the surface while a deep well pump is for those that go further than 25 feet down.

Turbine Pump

This type of pump is used for wells that need to produce a large amount of water. The motor is located on top of the well and there is a turbine shaft that goes down below the water level. There are impellers found at the bottom of the shaft to push the water up.

Cylinder Pump

These types of pumps are typically used for hand pumps or windmills. They are made of a cylinder on a rod that moves up and down to push the water to the surface. These are not used very often anymore since the invention of submersible and jet pumps.

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Related Questions

What are All the Parts of a Well System?

There are six or seven parts of a common household well system. It includes:

  • The well casing is the structure in the well that keeps the well from the groundwater open. The casing keeps the extra water and dirt out of the well and prevents contamination of the drinking water.
  • The well cap is a piece of plastic or aluminum placed on top of the well casing to keep animals, bugs, and dirt out of the well. The cap also has a vent that helps control the pressure while the well is pumping.
  • The well screen on the bottom of the casing helps keep sediment out of the well. They are typically made of a perforated pipe, slotted pipe, or a continuous slot.
  • The pitless adapter is the connection that lets the pipes carrying the water stay below the frost line. This helps make sure the frost-proof and sanitary seal is maintained at all times.
  • The well pump is the motorized unit that pumps the water from the well casing to the surface when it is needed.
What Does the Well Pump Do?

The well pump is needed to pull or push water from the well into your home, community, or business. The size of the pump and the pump motor depend on several things:

  • The amount of water needed
  • The peak water demand
  • The number of plumbing fixtures
  • The water level in the well
  • The well diameter

A pump is rated by the gallons per minute or gallons per hour and the horsepower of the pump motor depends on these amounts. For example, a common pump for home use may be 10 gallons per minute and that will need ½ or ¾ horsepower motor.

Most water systems also include a pressure or hydropneumatic tank, which is a water storage container. This is usually found in a utility room or basement but may also be underground in some cases. The pressure tank does several things including:

  • Providing a reserve supply of water for times of highest demand
  • Building up a new reserve supply of water every time the pump runs so it does not have to start and stop as often
  • To store the water and provide you water when the pump is not running
How Many Gallons Per Minute Do I Need?

To get the right size pump, you have to know the gallons per minute of water that will be needed from it. There are two ways to find out the amount of water per minute needed. To figure this out, you have to figure out how many water fixtures are in the house.

For example, if the well is for a family home with two bathrooms, a washing machine, dishwasher, kitchen sink, and one garden hose it will need about 10 gallons per minute. The two bathrooms have three outlets each (shower, sink, and toilet) so they each count as three.

Another way to determine the water demand is to figure out the seven-minute peak demand. The peak demand for any household water usage is in the morning or evening when the whole family is home. You would then multiply that by the number of gallons typically used by the fixtures in the home.

Finding out the horsepower of your pump should be as easy as reading it from the manufacturer’s guide. However, if that is not an option, there is a formula that will help you figure it out. The water horsepower needed equals the minimum power that is needed to run the pump.

  • TDH is the vertical distance water travels plus the friction loss from the pipe
  • Q is the water flow rate in GPM (gallons per minute)
  • SG is the gravity of the water
  • Water horsepower TDH multiplied by Q multiplied by SG divided by 3960
  • The actual power required is the water horsepower divided by the pump efficiency

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Patricia Oelze
Patricia Oelze

I am a DIYer who loves writing about anything home-related. When I am not writing, you can find me studying for my PhD in Psychology, photographing nature, and swimming at the lake with my grandkids.

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