What Size Sump Pump for Basement?

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Last Updated on February 3, 2022 by Bonnie C. Welling

So, how to choose the best sump pump for your basement? What size sump pump for basement is right for my home?

Let’s explore to learn.

How to Calculate the Sump Pump Size Requirement for your Home Basement?

Sump Pump Size

Without proper precautions, heavy rain and floods can damage your home badly. A sump pump can be a great solution to this problem. But a poorly chosen sump pump can’t help you at this point.

A sufficiently efficient sump pump will save you from different dangerous situations. For this, you have to choose the right sump pump for the basement.

Before selecting the sump pump size, it is essential to learn how to calculate the sump pump capacity. Below are a few simple steps to do so.

An extreme rainy day is a suitable day to measure sump pump size. First, turn on your sump pump and turn it off when the water goes back to the level of shut off. Then shut the pump off and wait for the next 1 minute. Water will flow inside the pump, and you have to measure out the sump pits water level that goes inside of it in a minute.

Since the maximum diameter of an ordinary sump pit is 18” and 1 gallon of water is equal to 1” of the sump pits inside water.

To calculate the water amount that will come into your pit during an hour of continuous rain, multiply the water level measurement of the sump pit that has risen within 1 minute with 60.

This result will lead you to the pumping capacity once multiplied by a “safety factor” 1.5.

Look at the below example to understand it clearly.

Let’s say a sump pit receives 30” of water in its pit in a minute and it is equal to 30 gallons.

Now the calculation will be: 30 gallons X 60 minutes X 1.5 = 2700 GPH (Gallons per hour)

2700 is the pumping capacity of a sump pump.

Factors to be remembered

If you want to stay on the safer side, follow the additional steps discussed below.

Consider measuring the inflow of the sump pump many times during excessive rainfall.

After identifying the measurement, it is time to learn about the term “lift.” Now you might be thinking, what does lift mean? It is the pump height at which the pump water needs to be pumped. Let’s say your home basement is 6 ft. tall. + the pump pit is 2 ft. tall, which means a total of 8 ft. water needs to be pumped by your selected sump pump.

One thing you will need to keep in mind higher lift will let the pump work harder. As a result, the pumping rate will get affected.

If you decide to buy a larger sump pump than your requirement, remember this will make the sump pump turn on and off frequently. This way, the sump pump’s lifespan will reduce.

What to look for when buying a sump pump?

After learning about the sump pump capacity, some other factors play a vital role in the sump pump performance.

Sump Pump Type

Pedestal and submersible are 2 types of sump pumps available in the market.

A pedestal sump pump is easy to maintain and installed above the sump pit. At the same time, a submersible sump pump requires installation inside a hole.

In terms of price, a pedestal is inexpensive than a submersible.

Both require a minimum of 20 ft. long pipe to connect and bring out water to the drainage system from the basement.

User Requirements

Every homeowner’s requirements are not the same. Depending on the condition, the sump pump size varies.

For example, some people live in areas where rain happens excessively while others live in dry areas. Don’t make a mistake buying a sump pump looking at your basement and home size.

You have to buy a sump pump based on its capacity. We discussed the capacity measuring process of a sump pump above. Read that section intently and choose your required model.


This is another essential factor that you can’t deny.

Never look at the sump pump size; learn the motor power. Sump pumps are sold based on their motor power and available with 0.5 HP, 0.25 HP, and 0.33 HP, among others. The drainage area connection to the sump pump will let you understand your home sump pump HP requirement.

However, most homeowners use a 0.33 HP sump pump. On the other hand, 0.5 HP is relatively less expensive, and many homeowners prefer this too.

In terms of performance, 0.5 HP discharges more water compared to 0.33 HP in similar conditions. Moreover, 0.5 HP’s lifting capacity is high too.

It is advisable to consult with a technician if you cannot determine your sump pump HP requirement.

Read More: Best Battery Backup Sump Pump

Last Words

Hopefully, this article helps find the answer to the question – what size sump pump for basement is suitable for my home?

Depending on the situation, budget, and capacity, you can find the best-suited sump pump for crawl space. Additional research is also necessary.

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