What Size Sump Pump Do I Need?

No one cares about the sump pump until they’re ankle-deep in water garbage in their basement. Then they race to the hardware store to buy the first sump pump they see, without even knowing what size sump pump they need.

You’ll need a sump pump in your basement if you reside near a large body of water or in an area where it rains frequently. This pump removes excess water from your home and sends it to a safe location. However, if you don’t have the right-sized sump pump, your property may not be secure.

Picking the right size sump pump is critical to ensuring your basement stays dry. The pump must be strong enough to push water up into your basin but not so much that it causes the motor to burn out.

Continue reading to find out how a sump pump functions and whether or not you should have one installed in your house!


What is a Sump Pump, and How Does it Function?

A small pump that removes water accumulated in a sump pit is called a sump pump. The pit is typically located in the basement of a home.

Water enters the pit through drains or by natural seepage. A float switch activates the pump once the water level reaches a certain height. When the pump is turned on, it will start removing water from the pit and release it to an area away from your house.

The sump pit, also known as a sump basin, is where the sump pump and water are kept. A float switch activates to turn on the sump pump when the level in your sump basin grows excessive. When the water level reaches a safe height, the switch disarms and shuts the sump pump.

Types of Sump Pumps

Sump pumps are divided into two categories: submersible and pedestal pumps.

Submersible Pumps

A submersible sump pump is placed directly into the sump pit. The entire unit is submerged in water, and the motor is cooled by the water surrounding it.

Submersible pumps are less likely to clog than pedestal pumps because they are not exposed to debris. They are also less likely to freeze in cold weather.

Pedestal Pumps

A pedestal sump pump sits outside of the sump pit. It uses a long shaft to reach the pit and remove water.

Pedestal pumps are less expensive than submersible pumps, but they are more likely to become clogged with debris or frozen in cold weather.

What Size Sump Pump Do I Need?

There are several factors to consider when picking the right size sump pump. The distance between the motor and the floor is probably the essential consideration. In addition, you’ll need a more powerful and higher horsepower pump if there are a lot of pipes – especially vertical ones – in your drain system.

If you purchase a too small pump, it will work harder and may not last as long. If you buy a too big pump, you’ll waste money on an unnecessary purchase.

The Right Amount of Horsepower

The right horsepower will ensure that your sump pump performs as intended.

1/3 HP Sump Pumps

Most homes with a typical water table only require a 1/3 HP sump pump. This is the most popular sump pump size and can easily handle most water tables. The 1/3 HP submersible sump pump can manage 6.5 to 10 feet of the vertical rise of the sump pump and a horizontally aligned pipe of a maximum of 25 feet in length with a 90-degree elbow.

1/2 HP Sump Pumps

A 1/2 HP sump pump is required in most cases for houses with a water table of the above-average range. A 1/2 HP submersible sump pump drains 35% to 40% more water than the previously discussed 1/3 HP sump pump. In addition, when discharging water, a 1/3 HP can manage a taller vertical lift, thanks to the greater height than it can handle compared to a 1/2 HP sump pump (7 to 10 feet).

3/4 HP Sump Pumps

A 3/4 HP sump pump can lift water up to 25% higher than a 1/2 HP submersible sump pump. This kind of pump can lift water up to 30 feet high and 200 to 250 feet horizontally.

The horizontal and vertical distance of the motor

The distance the motor will need to push the water is an essential consideration. The more pipe – particularly vertical – in your drain system, the more powerful and higher-powered pump you’ll require.

Vertical Piping

Vertical drain lines need a more powerful pump because they work against gravity. The greater the head height, the more horsepower is required. If the pump does not have sufficient power, it will be unable to force water up and out of the basement, resulting in flooding.

Horizontal Piping

Pipes that run horizontally require less power from the pump to move the water. The size of the pump is determined by friction and distance of discharge pipes. Therefore, a well-planned design may minimize piping when horizontal pipes are required to drain water out of your basement.

Frequently Asked Questions

What is the best size sump pump?

There is no one-size-fits-all solution when it comes to sump pumps. Every case and budget is unique. Therefore, you may need to conduct additional research to obtain the best pump for your house.

The best size sump pump for your home will depend on the distance the water needs to be pumped, the vertical height of the pump, and the horizontal length of the discharge pipe.

How big of a sump pump do I need?

Many homeowners wonder what sort of sump pump they require. However, the most significant factors to consider are head height, gallons of water, and other features and functions.

Do I need a 1/2 HP sump pump or a 1/3 HP sump pump?

The answer to this question will depend on the distance the water needs to be pumped and the vertical height of the pump. If you have a lot of pipes in your drain system – especially vertical ones – you’ll need a 1/2 HP sump pump.

How to know what size sump pump I need?

To determine the size of the sump pump you need, consider the distance the water needs to be pumped and the vertical height of the pump. If you have a lot of pipes in your drain system – especially vertical ones – you’ll need a more robust and higher horsepower pump.

Can a sump pump be too powerful or small?

If the pump is too tiny, it won’t keep up with the amount of water entering the basement. If the pump’s strength is too high, it will be “short-cycle,’” which means it will begin and shut down frequently. This can result in a pump that fails prematurely.

What’s stronger, 1/2 hp or 1/3 hp?

People often advocate the 1/2 HP water disposal over other models, including the 1/3 HP sump pump, since it is usually better built and is more powerful. Please remember that it is a low-powered disposer and should only be used for lighter use.


A sump pump is not necessary for all households, but it can be extremely beneficial. For example, a sump pump might not be required if you’ve never had flooding on your property.

Your basement and home determine the size of your sump pump. Next, you’ll need to calculate the capacity, figure out how powerful it must be, consider the vertical lift, and evaluate the friction head.



Bill is a DIY plumber, handyman, and homeowner with more than a decade of experience. He has replaced and repaired sump pumps, backup pumps, float switches, check valves, and many other things around his family home. An engineer and tinkerer at heart, he is always looking to see how things work and taking on new home projects that help him grow his skillsets. He is a husband and father of two boys, has a bachelors degree in Computer Engineer and minor in Mathematics and likes to make homebrew beer in his free time.

      Sump Pump Advisor