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Choosing the Right Water Pump Size - Comprehensive Guide


Water pumps are vital tools used in a variety of environments. They help move water from one place to another for various purposes including irrigation, draining flooded areas, etc. However, not all water pumps are created equal. Pump size is significant. An undersized pump will not meet demand, while an oversized pump will result in wasted energy and potential damage to the pump itself. BISON's comprehensive guide is designed to provide you with all the knowledge you need to choose the right pump size to safeguard your pumping business.


How to choose the correct water pump size?

The main factors to consider when choosing a water pump size include gallons per minute (GPM), total head lift (THL), suction head (SH), inlet/outlet size, and pressure. These are all crucial measurements to guide you in sizing your water pump as they help determine how much water the pump is capable of delivering and how quickly it can do its job.

Suction head (SH)

SH is the vertical distance that a pump can pull water up from a source such as a well. The higher you need to pump the water, the harder it is for the pump to overcome gravity to do this. 

If your well is 20 feet deep, you will need a pump with a SH rating of at least 20 feet. This number is significant for deep well applications or pond drainage.

Total head lift (THL)

THL is the total height from the water source to the final point. This number will give you the estimated "power" the pump needs to move the water a certain distance. To choose the right THL rating, measure the distance from the water source to the highest point where the water will be used.

Let's say your water source is 30 feet below ground and you need to send it to your garden on a hill 40 feet above the ground. In this case, you'll want a pump with a THL rating of at least 70 feet.

Gallons per minute (GPM)

GPM measures how many gallons a pump can deliver per minute. To choose the right GPM rating, consider how much water you need to pump for your specific application. If you need to irrigate a large field quickly, you need a high-flow pump. For example, if you need to move 2000 gallons of water to a 3000 square foot site in one hour, a pump with a flow rate of approximately 33 GPM would be ideal.


Pressure refers to the force that a pump can exert on the water. To choose the right pressure rating, consider how much force is required to move the water to its final destination.

For example, if you use a sprinkler system for irrigation, you need a pump with sufficient pressure to get water out of the sprinkler system. A pump with a pressure rating of about 40 PSI (pounds per square inch) is usually sufficient for most residential sprinkler systems.

inlet/outlet size

If you need a water pump with different outlet/inlet size options, all you need to know is that they work the same way regardless of size. A 4-inch dewatering pump will probably do the job faster than a 1-inch pump. Also, keep in mind that no matter what size inlet your water pump has, you must try to use that size inlet or suction hose. Never decrease the diameter of the inlet/suction hose.

Make the right choice

Selecting the proper water pump size is a critical decision that directly affects the efficiency and life of your water supply system. Remember that the correct pump size depends on your specific needs and application. To find the right pump size, evaluate your needs based on these factors. If necessary, contact BISON or use an online calculator for precise calculations.

Moreover, considering the type of pump, its energy efficiency, and maintenance requirements can help achieve sustainable and cost-effective water management.

Also, remember that quality should not be sacrificed for cost. Choose a reliable manufacturer for durability and efficiency. With a wide range of high-quality, durable, and efficient pumps, BISON are your go-to water pump supplier for all your water pump needs. We not only provide the equipment but also offer professional guidance to help you choose the perfect pump size tailored to your specific requirements.



What horsepower water pump do I need?

A 1/3 HP sump pump will suffice for most average-sized homes in areas with average water tables. Typically, 1/3 HP pumps can handle a 7' - 10' vertical lift from a sump if they have a 90-degree elbow and a 3' to 25' long horizontal pipe.

Will a higher horsepower well pump increase water pressure?

Replacing a smaller well pump with a higher flow well pump means more flow rate (gallons per minute) and increased pressure.

Can a water pump be too big?

A too-large pump can put too much pressure on the water pipes. Depending on the material of the water pipes and the number of connections involved in the overall water system, too much pressure could cause leaks or burst pipes.

What size water pump do I need to lift water 20 feet?

3/4 HP pumps have a pumping capacity of 20% to 25% more than 1/2 HP sump pumps. Pumps of this size can handle high vertical lifts of 20 to 30 feet and horizontal pipes of 150 to 250 feet.

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I am a dedicated and enthusiastic salesperson from BISON, and I am here to share my vast experience. Enabling you to receive our expert advice and unparalleled customer service.

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