What Is a Sump Pump and How Does It Work?

Posted by
John Woodard on April 24, 2024

One of the biggest nightmares for a homeowner is a flooded basement. Heavy rain and rising water leave behind enormous repair costs and structural damage if not dealt with properly. A sump pump protects your basement from the headache and expense caused by these high water levels. When selecting a sump pump for your home, it is important to know which type of sump pump best suits your needs. In this article, you can learn how a sump pump works and how to choose the right one for your home.

What is a sump pump?

A sump pump is a device that moves water from your basement to the outside of your home. A sump is a naturally constructed pit, usually a hole carved below the main surface of your basement floor. This pit, known as a basin, holds the sump pump. The pump is equipped with valves that sense escalating water levels or pressure. When the water level gets too high, sump pumps automatically pump excess water out of the basement and away from your property using a discharge line. This line, called an effluent, connects the sump pump to a designated drainage area.

How does a sump pump work?

A sump pump is a mechanism that detects elevating water levels and pressure to ensure that these levels do not rise too high. These pumps use a switch to detect water levels in the basin. When the switch is activated by a rising water level, the pump turns on and directs water into a discharge pipe and away from the home’s foundation. A pump can be powered electrically, by battery, or by water. Primary pumps are typically wired in, but many sump pump systems contain a backup pump that is powered by either water or a battery in case of a power outage.

Do I need a sump pump?

Sump pumps are necessary in homes prone to flooding. Whether it is from above-average rainfall or basements built below the water table, flooding can be disastrous for your home and your health. Even if your home does not flood, moisture can cause several types of mold that increase the risk for upper respiratory infections, allergic reactions, and asthma complications. If you don't have a way to move water outside, it will accumulate and eventually flood or dampen your basement.

Where should a sump pump discharge?

Your sump pump water should discharge to a designated area, such as a dry well, a creek or pond, or even a neighborhood drain. Be careful not to set your drain point somewhere that water will return to your home. Ideally, direct it 10 to 20 feet away from the foundation of your home. Some cities have building codes that determine where your sump pump can drain, so it is always best to check with your local government. Note that you may need to attach an extended drainage hose and increase the horsepower of the sump pump to compensate.

sump pump diagram

Types of sump pumps

There are 4 common types of sump pumps: submersible, pedestal, battery-powered backup, and water-powered backup.

Submersible sump pumps

Submersible pumps contain the pump and motor in one unit. They sit submerged and closed inside a basin in your basement. Because submersible pumps are completely submerged in the water basin, they are often quieter, save space, and clog less than a pedestal sump pump. However, because of the effects of water submersion, they may not last as long as other sump pumps. Despite this downside, a submersible sump pump is still the best option for homes with major flooding concerns.

Pedestal sump pumps

Unlike a submersible sump pump, a pedestal sump pump consists of a separate motor and pump. The motor sits on a pedestal above the basin, with a hose running to the basin where the pump is placed. The pump sends water through the hose and out to your designated drain area. Because the motor is not submerged, it often has a higher lifespan than other sump pumps and can be accessed easier for maintenance issues. However, it also means it can be louder and take up more space than the submersible pump.

Battery-operated backup

A battery backup sump pump is a great way to provide some extra security against flood damage. A battery backup with a float switch allows your sump pump to operate even when your power is out during a storm when you need it the most. When water rises in the basin, the float switch is triggered, sending your battery operation into action.

Water-powered backup

A water-powered backup clears the water in your basin through increased water pressure. The advantage of a water-powered system is that there's no need to monitor the backup or replace any batteries. The use of additional water raises your water bill significantly and is a bit controversial. Some cities do not allow them to be installed.

What is the best sump pump for my home?

The best sump pump for your home has appropriate horsepower to deal with the demand in your basement. If you select a sump pump with a lower horsepower than necessary for the flooding in your area, you are still at risk of flooding. At the same time, a higher horsepower than necessary will cause cycling, turning on and off repeatedly, which lowers the lifespan of the pump. If your home is deep into the water table, has heavier seepage issues, or requires a farther drainage point, a one-half horsepower submersible pump can give you the added power you need. If you experience major flooding issues frequently or use the pump for outdoor or commercial uses, a sump pump with 13000 GPH will take care of the saturation.

Sump pumps with a cast iron core last longer than those with a plastic or stainless steel core. Heat presents a dangerous threat to electric motors because they develop heat themselves. The cast iron core sits in contact with the motor and dissipates the motor’s heat far better than plastic or stainless steel. You may also wish to purchase a pump that comes with an alarm. This will warn you if the water level rises too high because of extreme water volume or pump failure.

Types of sump pump switches

Sump pumps can operate on a switch system. A switch allows the pump to be turned on independently. While they achieve the same result, some switches operate differently from others. Below are several types of switches and how they work.

  • Diaphragm switch: This switch operates much like your diaphragm, flipping concave as the pressure rises and back when it lowers. It is the most common type of switch because it rarely gets stuck on or off.
  • Pressure switch: A pressure switch senses the amount of pressure in the water as it rises and triggers the action of the pump at a specific threshold.
  • Vertical float switch: The vertical float switch is a magnetic switch that slides up and down a rod on the pump. As the water level rises, the float ascends the rod and kicks the pump on. When the water level descends, the switch lowers and tells the pump to turn off.
  • Tethered float switch: The tethered float switch is tied to the pump and floats in the basin. When the water rises and the switch cannot float any higher, an electrical signal is sent to the pump to activate it. When the switch cannot float because the water level is too low, an electrical signal tells the pump to shut off.
  • Electronic switch: The electronic switch works not by any float, but by sensing the water pressure within the basin. As the water rises, so does the pressure, setting off the probes and switching on the pump.

Sump Pump Accessories

There are also additional add-ons to consider for your sump pump. Accessories like a water alarm attachment provide a last line of defense to alert you when your sump pump fails before the damage is done. A discharge hose helps extend your drainage point away from your home.

Cost of sump pump installation

Generally, a basement submersible sump costs anywhere from $100-$400 depending on the horsepower and flow rate, and $500-$1000 prices are common for sump pumps intended for commercial use.  For sump pump installation, you will often pay more in labor costs than for the pump itself. Professional installation costs range from $600 to $3000 depending on factors that vary by installation. While professional installation can be pricey, a well installed sump pump will save you money over a poorly installed system in the long run.

5 factors that impact sump pump cost

Below is a list of considerations for calculating the cost of a sump pump in your home.

1. Type of sump pump

The type of sump pump you choose for your home will determine your cost. Factors such as the material used to make the sump pump, size, horsepower, and additional features, such as a backup battery or a specified switch type, can all contribute to the cost. 

2. Basement material

The floor of your basement can also play a part in the cost of installation. If your basement is made of cement or concrete, then the floor will need to be removed in the lowest point of your basement where you plan to install the pump. The thicker the cement, the higher the cost of labor.

3. Drainage

If your city requires a drainage point a distance from your house, yard drainage lines or extension hoses can increase the cost of installation. They can also be hazards to your yard or even freeze in the winter.

4. Permits

The cost of a permit varies depending on location, so it is best to consider it beforehand. The guidelines will also help you factor the cost of the job.

5. Licensed professional

Installing the sump pump yourself can cut costs dramatically if you know what you are doing. If you are unsure, it is best to go with a licensed professional. Professional installation costs are cheaper than treating a flooded basement.

How long do sump pumps last?

Sump pumps have a lifespan typically between 7 to 10 years depending on the amount of usage. Sump pumps can fail due to installation, machine, and lifespan errors. If you are installing the pump yourself, make sure you are familiar with the process. The money you save doing it yourself is nowhere near the money you will lose in water damage if you install it incorrectly. Also, pump errors can result from continuous cycling or switches that get stuck on or off.

sump pump replacement

Do I need a battery backup sump pump?

While sump pumps are effective at removing water from a home, many factors can cause them to fail. Owning a backup pump ensures that you will not fall victim to water damage when your primary sump pump fails. Some primary sump pumps are wired into the home and do not have a battery backup, so flooding is a concern when power is lost. Having a backup that is either water-powered or has a battery backup will protect your home during heavy storms that turn your power off. While owning a backup sump pump is not required, it is recommended for the health of your home.

Signs of a faulty sump pump

If your sump pump is making loud noises, running for an unusually long time, cycling irregularly, or is older than ten years, it is very likely you are due for a sump pump replacement.

Learn more: How and when to replace your sump pump

Loud noises

Loud noises coming from the sump pump's pit indicate that there is a serious problem with your pump. As the pump approaches the end of its lifecycle, the motor will start to make roaring sounds as it pumps the water away from your home. All sump pumps will make some degree of noise as they pump water out of the basement, but the noise levels should never reach you upstairs in your house. Rattling, clanging, and screaming motors all indicate that the motor is approaching failure or that the pump was installed incorrectly to begin with. If the discharge lines running from the sump pump's pit are angled sharply, this will generate a great deal of noise. The water will slam into the tubing angles, sending banging noises throughout the basement. Consider wrapping the pipes in insulation to dull the noise or call a plumber to reroute the discharge pipe in a more streamlined fashion. 

Loud noise can also indicate a damaged impeller. If the pump's impeller has become choked by debris like leaves, dirt, and sticks, the pump will screech and rattle as it attempts to suck water out of the basin. If the impeller becomes broken or otherwise damaged, it can make loud rattling noises when in use. When the pump is not in use, consider removing the pump and inspecting the components to make sure they have not become clogged or injured. 

Constantly running

If the pump is constantly running, this indicates that your pump is either at the end of its lifespan or rapidly approaching it. A sump pump should never cycle continuously. It is entirely possible the pump is altogether the incorrect size. A pump that is too small for the volume of water it is tasked with displacing will perpetually struggle to keep up with demand. This will exhaust the pump, overwork the motor, and lead to premature failure of the pump. 

A pump that is constantly running could also be the result of a damaged or jammed float switch. The float switch is the apparatus that triggers the pump to turn on. Float switches are lightweight devices that will rest on the surface of the rising water. Once the water in the basin reaches a predetermined height, the switch will alert the pump to begin displacing the floodwaters. If this float switch becomes tangled in wires or pipes or jammed by debris, it will perpetually signal the pump that there are elevated water levels. The float switch can also become jammed if the sump pump shifts within the basin and the switch presses against the walls of the pit. A stuck float switch keeps the pump running constantly, forcing the pump to exert an unsustainable amount of effort. The strain placed on the motor by this will cause failure far before the designed lifespan of the pump. If you hear your pump running perpetually, it is wise to quickly identify the root of the issue before your pump wears out entirely.

Cycling irregularly

A float valve positioned too low in the basin will also place extraneous work on the pump. If it only takes mere inches of water to trigger the pump's cycle, the pump will kick on and off constantly. This short-cycling of the pump places strain on the pump and its mechanical components. If your pump is taking too long to empty out your basin, then the pump probably does not have enough horsepower to perform its job. A pump that is unable to empty out the basin during a typical amount of rainfall will quickly become overwhelmed in the event of a serious storm or flooding.

Old age

No matter how good your sump pump is, it will need to be replaced about once every 10 years. While some pumps may last longer than a decade, problems will be more likely to arise after this age threshold. Replacing the pump every 10 years reduces the risk of water damage and high repair costs in your home.

Sump pump alternatives

French drains

French drains work to prevent water from pooling by creating paths of least resistance for water to drain. Since water always drains in a path of least resistance, creating paths of least resistance that will prevent water from pooling prevents an area from flooding. French drains make use of artificial paths to create ideal flow for water around a home. They use a perforated drainage pipe that transports water into a drainage system and away from the home.

While French drains are effective, they do not completely prevent water from entering a home. If you live in a rainy area, you will need a portable sump pump in conjunction with your French drain.

Waterproofing compound

Basements can flood because of holes in a wall that water can slip through. If water leaks through the walls in your home, adding waterproof caulking compound to the cracks can help reduce the amount of water reaching your basement.

caulking compound

Gutter maintenance

Basements can often flood because gutters do not effectively move water away from the home. Leaves, twigs, dead insects, and other debris can clog downspouts and gutters and prevent them from draining water. Downspout filters and gutter guards are excellent at ensuring water does not back up in your downspouts. If you do not have either gutter guards or downspout filters, regularly cleaning your gutters will prevent them from causing flooding in your home.

Learn more: Types of downspout filters

Sloping the ground

Sloping, also known as grading, involves creating a slight slope around a home before construction. As homes age, this slope can become level or even reversed. Ideally, a home’s soil should drop 1 inch for every foot of ground in the first 10 feet surrounding the home. While sloping is always done during construction, adding soil around a home can help correct grading that deteriorates over time.

Learn about other pump types: Well pumps | Booster pumps | Peristaltic pumps | Bilge pumps


If you have any additional questions, please do not hesitate to contact us.

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