How to Determine Which Sump Pump Size You Need

In general, a sump is a collection bowl that holds liquids. For instance, your car has a sump to collect oil. As for your home, a sump pump is a vital plumbing appliance that provides a long list of benefits and an unparalleled level of security. So, if you are on the market for a new sump pump, it is important to procure the proper unit for your home or office. Otherwise, you could be in for a plumbing disaster down the line. This obligation starts with determining which size sump pump you need.

Continue reading to learn how to size a sump pump, correctly.

Indianapolis Sump Pump Services 317-784-1870
Indianapolis Sump Pump Services 317-784-1870

Sump Pump Operation

In order to know which sump pump make and model is best for your home or office, it is necessary to understand some basics surrounding sump pump operation and maintenance. Sump pumps are designed to eliminate excess flood water filtering through loose aggregate and soil surrounding a property’s foundation. In most cases, they are installed in a small pit that is dug in the floor of a basement, usually 2 feet deep and 18 inches wide.

The pump portion of a sump pump system is designed to detect water levels within the sump pit using a specialized float device. When water in the sump pit gets too high, the float completes an electrical circuit, turning on the pump and sending the excess water away from the property through a series of plumbing pipes. Such systems also have a one-way “check valve” that is designed to prevent expelled water from returning to the pit.

Maintenance and Installation

Because sump pumps require electricity to work, it is vital to also have a backup sump pump battery (or an alternative back-up power source) in the case that your power goes out. In regions where precipitation patterns are consistent or high, it is necessary to have an entire back up sump pump system to manage the larger flow of water. As with anything electrical near water, it is critical to have your sump pump connected to an outlet that has a ground fault circuit interrupter (GFCI).

Sump Pump Size

When you are talking about sump pump size, you are really referred to output. Sump pumps come in a wide range of make and models, all with varying outputs. This is basically the capacity to which the sump pump can displace water. Factors that will influence the sump pump output you need include property size, location of pump, distance of plumbing pipes, and more.

While shopping around, look for a chart on the side of the sump pump. This chart will depict how much flow and head values. Flow refers to how many gallons of water per minute the sump pump can move, while head refers to how far the water must vertically travel from the pump to the outlet pipes. These values are inverse, which means as the flow rate lowers, the head rate increase. You see, a sump pump must use more energy to push more water farther upwards. Therefore, if you have a sump pump that is not the proper output, it can be wasting energy or using up too much.

In order to know which sump pump size you need, you must calculate your flow rate. In order to do this, you have to wait for a rainy day. Here’s how:

On a rainy day, run your sump pump until the water level is below the shuts off level.

Then disconnect the power and measure the distance to which the water rises in 1 minute. This is your flow rate.


Next, multiply your flow rate by 1.5, which will give allowance for severe storms and flooding.

Then measure the vertical distance from the bottom of the basement to the sump pump outlet pipe. This is your head distance.

Now that you have flow and head values, refer to the chart on the side of your sump pump to see if it is sufficient.

A Fair Warning

A power rating of 1/3rd horsepower is recommended for the average residence, however, aside from flow rate and head values, there are several other factors that can impact the proper sump pump size you need. For instance, components like elbow joints, check valves, and narrow piping, can increase friction levels, thus requiring a more powerful unit. That is why it is strongly recommended to consult with a licensed plumber to learn the best sump pump options for your home or office.

Sump Pump Service and Repair in Indianapolis

Call Weilhammer Plumbing Co. Inc. at 317-784-1870 when you need skilled and dependable Indianapolis sump pump services you can trust. Our licensed plumbers offer a wide range of standard and master plumber services for both residential and commercial properties, including help with sump pump installation, replacement, repair, and maintenance. We also sell top-of the-line Zoeller sump pumps at wholesale price! Get the best package deal on a brand new sump pump that includes installation and maintenance! Request a free estimate, today.