Sump Pump

What is a sump pump?

A sump is a simple device that detects water in the sump and moves it away from the property through a network of pipes. Many homes have a small pit that is dug into the floor of the basement. This is used to collect water that filters through.

Sumps are most of the time only about 2 feet deep and 18 inches wide. When the water rises to a certain level, a floating switch will then turn on and that engages the pump. Most of the time this will contain a one-way check valve that prevents expelled water from flowing back into the pit.

Many sump systems have alarms to alert the homeowner if water rises past a certain point. This will indicate to the homeowner that the sump pump is failing. Modern smart pump alarms can even send alerts right to your phone. There are also sump pump alarms that indicate the backup pump has been engaged, meaning you should check the primary pump.

Sump pumps require electricity. Since the sump is operating near (or in) water, it’s important that the outlet you connect the pump to has a ground fault circuit interrupter (GFCI). It’s always a good idea that you connect your sump to a backup power source. Flooding often happens when a severe storm happens. This will most often cause power failures in your system. If your sump pump detects water but has no power to operate, it is not going to be able to protect your home from all the after damage. So at that point, you might as well not even have one.


Types of sump pumps

Sump pumps are either primary or backup, and your system should have one of each. Primary sump pumps do most of the work most of the time. The backup sump pump is only there to tag in if the primary pump fails, or if it can’t keep up to the water inflow.
There are two main types of sump pumps: submersible and pedestal. Either type can come in the primary or backup variety. You can also divide backup sump pumps based on their backup power source: battery or water.

Submersible pumps

Submersible sump pumps are bulky devices. They sit right inside the sump pit, and function while underwater (hence, submersible). Since they sit in a pit, they run quieter than pedestal pumps but are usually more expensive. They’re also harder to access for maintenance.

Pedestal pumps

Pedestal pumps are long, upright devices with the pump motor sitting on top and the intake device, or impeller, at the bottom. The motor on a pedestal pump isn’t meant to get wet. These are less expensive and easier to access for repairs compared to the submersible variety, but some plumbing experts consider them less reliable than submersible pumps. They’re also louder, as the motor sits above the sump pit.

submersible sum pump
Battery operated backup

The most common type of backup sump pump is the battery-powered backup. These don’t replace a primary pump. Instead, they spring to life when the primary pump cuts out due to a power failure or some other reason. Most often, they’re connected to a large battery (like a marine or car battery).

Water-powered backup

Water-powered backup sump pumps aren’t connected to an electrical current; they’re powered by good, old-fashioned water pressure. They have the advantage of unlimited runtime, but there are some restrictions. Water-powered pumps need a strong, steady flow of water, like the high-pressure flow of a city water system. In a home with low water pressure, or pump-powered well sources, water-powered sump pumps won’t work correctly. They’re also more challenging to install than their battery-powered counterparts.

Combination sump pump

It’s also possible to buy an all-in-one sump pump that includes a primary pump and a backup pump in the same package. It may be more cost-effective than buying each separately, but they tend to be large and may not fit in smaller sump pits.

What size pump do I need?

Sump pumps come in a variety of outputs. Each pump comes labeled with a reference chart explaining how much water it can displace.

The chart contains two columns: head refers to the vertical distance that water must travel from your sump pump to the outlet pipe, and flow refers to the volume of water that the pump can displace (in gallons per minute).

These figures are inversely proportional; for any given pump; the flow reduces as the head increases. That’s because the pump must work harder to push the water further up, thus decreasing its efficiency.

Determine flow rate

To figure out your flow rate, wait for a rainy day and run your pump until the water drops below the shut-off level. Then, disconnect the pump from all power sources and measure the distance the water rises in one minute. For an 18-inch sump, one inch of water is equal to one gallon. In a 24-inch sump, one inch of water is equal to two gallons. Once you’ve calculated the flow rate, multiply it by 1.5 to allow a margin for severe storms.


Next, measure the vertical distance from the bottom of your basement to the outlet pipe. The outlet is usually at or around ground level. Then, reference the chart on your pump to see if the flow rate is sufficient for the head distance.
Experts recommend a power rating of 1/3 horsepower for average homes. Take into account elbow joints, narrow pipes, and check valves as well; these increase friction, potentially requiring a more powerful pump. If you’re in any doubt, contact a plumber to determine whether your sump pump is sufficient.

Maintaining a sump pump

Sump pumps require scheduled maintenance. Dirt, sand, and other debris can clog the pump and prevent it from working at capacity during an emergency. Most homeowners only find out that their pump isn’t working when it’s too late; we recommend servicing your sump pump every 6 months.