What is a Sump Pump & How Does it Work?

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A sump pump provides a simple solution to send water away from your basement. Sump pumps move water up and away from your home to prevent damage from snowmelt or heavy rain. You can usually save money on your insurance premiums by installing a sump pump. 

There’s a good chance that you already have a sump pump in your basement if you live in an area that’s a high flood risk. But you might be considering installing a sump pump if you don’t have one already. 

In this guide, we’ve shared everything you should know about sump pumps, including what they are, how they work, and whether they’re right for you. 

πŸ“Œ Key Takeaways:

  • A sump pump is a mechanical device that draws water out of a sump pit, which prevents moisture accumulation and flooding.
  • There are two common types of sump pumps: submersible pumps and pedestal sump pumps.
  • When choosing a sump pump for your home, consider your budget, your required pump size, maintenance, and servicing requirements.

🚰 What Is A Sump Pump?

A sump pump is a device that moves water up and away from your basement through a series of pipes.

To understand how a sump pump functions, we need to also understand sump pits.

A sump pit is a hole that’s set into the floor of a basement. When it rains or snows, water from the surrounding ground seeps through your home’s foundations and into the pit. 

The sump pump detects when water is present in the pit, and pumps the water away from the basement through pipes.

Sumps have a diameter of around 18 inches and a depth of around 2 feet. A sump pump uses a float switch, which is connected to the pump and triggers it to draw water once it rises to a certain level. An essential component of a sump system is a one-way check valve, which stops water from flowing back down into the pit. 

Sump pump

It’s common for a sump pump to sound an alarm if water exceeds the level that would usually trigger the pump to activate, since this typically means that the pump is failing. You can connect some sump systems to a smart device, so you can receive alerts whether you’re at home or elsewhere. Many sump systems also have a backup pump that will trigger if the primary pump fails, preventing flooding. 

A sump pump only works with access to electricity. The pump needs to be safely installed and connected to an outlet that has a ground fault circuit interrupter (GFCI). If your home often experiences power outages, particularly during storms, you should also consider a backup power source, like a generator, for your pump.  

βš™οΈ Types Of Primary Sump Pumps

The two most common types of primary sump pumps are submersible pumps and pedestal pumps.

Submersible Sump Pumps

Submersible sump pumps sit below the ground. They’re either installed inside or outside of your home, and are designed to work underwater. The pump is submerged underwater, and uses centrifugal force or an impeller once the water level in the sump pit rises to a certain point. 

There are a few advantages and disadvantages of submersible sump pumps: 


  • They take up little to no space because they’re installed below-ground
  • They’re quieter because their underground location muffles their sound
  • They’re powerful and can quickly draw water out of a basement or crawl space


  • They’re harder to maintain because they’re located both underground and underwater
  • It’s harder to see and hear if the pumps have broken down because of their underground location
  • They’re often the more expensive option (both to purchase upfront and to maintain)
Submersible sump pump

Pedestal Sump Pumps

Pedestal sump pumps are designed to sit above the water level in a sump basin or pit. These pumps are long devices, with a motor that sits on the top of the pedestal, and the impeller at the bottom, submerged in the sump pit.

When the water level rises, the impeller spins quickly, creating centrifugal force that sends water up through the pedestal and through a connected pipe, which carries it away from the building. 

We’ve listed the pros and cons of pedestal sump pumps below. 


  • They’re easy to install and maintain because they’re positioned above-ground
  • They’re more affordable than submersible pumps, with prices starting at $100
  • They’re longer lasting because the pump isn’t submerged underwater, so the motor is less susceptible to water damage


  • They’re noisier because they’re positioned above the ground, so there’s nothing to muffle their sound
  • They take up more space because of their above-ground location
  • They’re not aesthetically appealing
Pedestal sump pump

πŸ”‚ Types Of Backup Pumps

As we mentioned, most sump pumps have a backup pump of some description. In most cases, you’ll have to buy a backup pump separately from the main pump.

Some pumps are combination pump, meaning that the primary and backup pumps are sold in the same package. You can often get a good deal from buying both pumps together. 

The most common types of backup sump pumps are: 

Water-Powered Backup Pumps

Water-powered backup pumps are powered by water pressure. The good thing about these pumps is that they can run for as long as needed because they’re not restricted by battery life or hindered by a failing power supply, but they only work if your water supply is strong and steady.

Most homes on municipal water supplies should do fine with a water-powered backup pump, but if you have a private well supply where water pressure is hit-and-miss, it might not provide enough force to power this pump type.Β 

Battery-Operated Backup Pumps

Battery-operated backup pumps are powered by a large battery. If the main sump pump fails or cuts out, the stored power from the battery backup pump will be used instead.

Battery-operated pumps use large batteries that can supply enough power to last for around 5-7 hours of continuous pumping or up to 3 days of non-continuous pumping before the battery runs out. This pump type is more popular than the water-powered backup pump. 

πŸ“– How To Choose The Right Sump Pump For Your Needs: 4 Things To Consider

Consider the following things when deciding on the right sump pump for your home: 

Your Budget

Price is the first place to start. 

You’ll need to buy a pump that’s within your budget, or establish a savings plan to help you save the money you need to buy a new pump within the required time frame. 

A brand-new sump pump is typically $100-$500. There are several factors that affect the cost of a sump pump, including: 

Cost FactorWhat You Need to Know
The pump typeSubmersible pumps are more expensive than pedestal pumps
The pump sizeThe bigger the pump, the more materials you’re paying for, so the higher the upfront cost
Sump pump installationDIY installing the pump will be cheaper than hiring a professional, and different installers have different prices
Sump pit installationIf you don’t already have a sump pit, that’ll cost around $2,500-$5,000 extra
Build quality and materialsThe better the pump quality and the more durable the materials, the costlier it’ll be
ManufacturerCertain renowned manufacturers can charge more for their products than other lesser-known brands

We would always advise spending as much as you can afford on the best-quality pump, even if it means waiting a few extra months to be able to afford a slightly costlier pump. The pump will quickly pay for itself if it provides a reliable, quality performance throughout its long lifespan. 

Pump Size

You also need to carefully consider the size of your pump. 

Different sump pumps have different pumping capacities. When you buy a pump, you should be able to choose between a number of outputs, and the manufacturer should provide a reference chart that tells you the amount of water that each pump size/capacity can displace. 

There are two measurements that you should be aware of: 

  • Head: The distance that water needs to travel vertically from the sump pump to the outlet pipe
  • Flow: The amount of water that the pump can displace (measured in GPM, or gallons per minute)

The bigger the head (or the further the water must travel), the lower the flow. On the other end, the smaller the head (or the shorter the pumping distance), the higher the flow. That’s because the work required by the pump depends on how far up the water needs to be pumped. 

You need to accurately size your new sump pump based on the amount of moisture that enters your sump pit and the distance that the water has to travel out of your basement.

If you’re replacing an existing sump pump, you can measure flow rate with the following process: 

  1. Wait for a very rainy day, then run the pump until the water has receded and the pump shuts off. 
  2. With the pump off, wait for 1 minute, then measure the new height of the water. 
  3. Let’s assume that your sump pit measures 18 inches in diameter (the standard). Every extra inch of water in the pit equates to about 1 gallon. 
  4. Once you’ve measured the number of inches that the water level has risen by, multiply this number by 60, which tells you roughly how much water would enter the pit in 1 hour of constant rain. 
  5. Multiply this figure by a safety factor of 1.5. This will give you your ideal pump capacity.

If you don’t currently have a sump pump already installed, ask your pump installer to help you determine a suitable flow rate for your new pump. 

Measuring sump pump size

Sump Pump Maintenance

On the whole, sump pumps are quite reliable and don’t need a lot of maintenance. But, like any equipment, sump pumps do require some basic maintenance to keep them in good working order.

You’ll need to consider maintenance before you buy a sump pump and confirm that you’re happy to commit to these jobs before you spend your money.

Some of the basic sump pump maintenance jobs are:

  • Check the outlet and the cord to make sure they’re still in good shape. Make sure the pump is still plugged in and working. The GFCI breakers may occasionally trip, especially in damp areas. Checking the pump occasionally means you’ll know when this happens and can reset the GFCI.
  • Make sure the pump is in an upright position. It may tilt at an angle due to the vibrations while the pump is in operation, causing the float switch to jam and preventing the pump from activating when needed.
  • Check the pump’s performance. You can do this by pouring a bucket of water into the pit and waiting for the pump to start automatically. Check that the pump continues to run until the water has drained.
  • Get the pump serviced. Most professional installers recommend servicing sump pumps once a year.
  • Clean the sump grate. Remove the pump from the pit and clean the bottom grate to remove any small stones. Do this at least once every three months.
  • Check the outlet pipes. They should have tight connections, with no leaks or holes.
  • Clear the vent hole. Check that the discharge pipe’s vent hole is clear, and remove debris if necessary.

Most sump pumps have a life expectancy of around 10 years. The lifespan of a pump depends on how well you maintain it, as well as factors including the quality of the pump’s build and the type of water that’s being pumped.

Other Considerations

There are a few other considerations you should also make when choosing a sump pump for your home:

  • Whether you buy a water-powered or battery backup sump pump (if any)
  • Whether you opt for a manual or automatic sump pump (we recommend automatic for convenience)
  • The pump’s cord length (it’ll need to be long enough to reach a ground fault circuit interrupter (GFCI) outlet – you shouldn’t use an extension cord)
  • The pump’s voltage (most sump pumps for residential use have standard circuits of 110 volts)
  • Whether you buy a pump with an alarm system that alerts you if the pump fails
  • The required distance of the discharge pipe and the required head pressure in relation to this

If you’re hiring a professional to install your sump pump system, they should be able to advise on many of the above considerations.

For instance, a professional can help you to correctly size your primary pump, quote you for the cost of a submersible sump pump vs a pedestal sump pump, and work out how much discharge pipe is needed.

If you’re installing a new pump rather than simply replacing a pump, we especially recommend hiring a professional to handle the installation process for you.

Plumber installing a sump pump

πŸ€” Do You Need A Sump Pump?

Not everyone needs a sump pump. You don’t need to spend money on a pump unless your situation calls for it.

For example, if your region is consistently warm and dry and you’ve never noticed standing water in your basement, there’s no point in buying a sump pump.

On the other end, if your home sometimes floods and you have issues with damp and mustiness, you could benefit from a pump that will prevent moisture damage to your basement.

Sump pumps can be used alongside other waterproofing solutions to keep your basement safe and protect any appliances and possessions in the space.

How do you know if moisture is getting into your home?

Try sticking a 2-foot square-shaped plastic piece onto your basement wall with tape. For the most conclusive results, tape several plastic pieces onto different locations around the room. Then, wait a couple of days before checking behind the plastic. If it’s wet, moisture is a problem, and you could likely benefit from a sump pump.

πŸ”  Other Anti-Moisture Solutions

So, you’re planning to replace your current sump pump or install your first sump pump system for your basement.

But are there any other anti-moisture solutions that you should invest in to protect your home?

Yes – we recommend also installing a dehumidifier. This will remove any moisture from the air in your basement and protect the space from damp.

You should also check the condition of your downspouts and gutters and repair or replace them if necessary. Make sure all downspouts direct water at least 6 feet away from the foundation of your home.

Dehumidifier in basement

πŸ”š Final Word

If you were wondering, “What is a sump pump?”, hopefully this article has now answered your question.

You should now be confident about the different types of sump pumps, and which sump pump systems are best for your situation. You should also be aware of the advantages of a backup sump pump if the primary sump pump fails.

Check our FAQs if you have any other specific questions about sump pumps for your home.

❔ FAQs

What is the purpose of a sump pump?

The purpose of a sump pump is to remove excess water that has accumulated in a sump pit, usually in your home’s basement. This prevents your home from being damaged by moisture and greatly reduces the risk of flooding.

Is it worth buying a house with a sump pump?

It’s only worth buying a house with a sump pump if you live in an area with heavy rainfall and the house would otherwise have a moisture issue. You don’t need to buy a house with a sump pump if you’re buying in a dry region or if the house doesn’t have moisture issues.

Is a sump pump the same as a septic tank?

No, sump pumps and septic tanks are entirely different things. Sump pumps draw excess water away from your basement, while septic tanks collect wastewater and sewage from your home’s fixtures and appliances. You might think they’re similar because they both look alike and are both typically installed in a basement, but don’t get them confused – they have very different purposes.

Do all houses have sump pumps?

No, not all houses have sump pumps. Some houses don’t need a sump pump, while some houses do need one, but don’t have one installed. You can identify a sump pump in your basement by looking for a formed pit or hole in your basement floor that has a pipe leading out of it and away from your house.

What triggers a sump pump to run?

A sump pump is triggered to run when water in the pit rises, and the float switch reaches a certain height. This will initiate the pumping sequence, and the pump will pump water until the water level has dropped again, preventing a flooded basement.

Can you leave a sump pump on all the time?

Yes, you can and should leave your sump pump on (i.e. connected to your power supply) all the time, which will protect your home from excess water at all times. However, the pump shouldn’t be constantly running (i.e. pumping) because this will cause the components to wear quickly, potentially leading to pump failure. The pump should only kick in once water enters your basement and reaches a certain level in the pump pit.

How much does it cost to replace a sump pump?

The cost of replacing a sump pump is around $100-$500, depending on the pump size and style, and how much work is required to replace the pump.

Where does the sump pump drain to?

A sump pump drains to a designated drainage area at least 6 feet away from your home. This could be a creek, a pond, a dry well, or a local drain. Ideally, the drainage area should be 10-20 feet away from your home.

Should I avoid a house with a sump pump?

No, you shouldn’t avoid a house with a sump pump. The sump pump simply tells you that the house is protected against moisture and flooding. You’ll just need to be prepared to commit to occasional maintenance and repairs to prevent sump pump failure, which could result in flooding.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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