Sump Pump Information Guide

Main Content Starts Here

What is a sump pump?

Sump pumps are small pumps installed in your basement or crawl space that are designed to remove water and prevent the area from flooding. The pump is installed in the lowest part of the space, usually in a sump pit. Water is channeled into the pit via drains or naturally accumulates there through the surrounding soil and gravel. As water builds up in the pit, the sump pump turns on and pumps it out through a discharge pipe, moving it safely outside of the home to a location where it can drain away, keeping the remainder of the basement or crawlspace dry.

Anyone with a basement should consider installing a sump pump, even if the home is not in a commonly flooded area. Depending on the size of the system that you need and whether you have a professional install it or you do it yourself, sump pumps can be relatively inexpensive – especially when compared to the cost of a basement that's been ruined by flooding. Even if only an area of your basement floods, the water can encourage the growth of mold and mildew, making the space unattractive and unhealthy. Having the extra security of a sump pump, knowing that your home, belongings, and family are protected, can give you added peace of mind.

What's the right pump for me?

Recognizing that you should have a sump pump and understanding what type you need are different issues. There are many options available, and choosing the right sump pump for your home depends on a variety of factors.

  • Do you need a pedestal or a submersible sump pump?
  • How much horsepower do you need?
  • Should you choose cast iron or thermoplastic? 

Finding the right pump shouldn't be a struggle – here are answers to some of the most frequently asked questions about sump pumps.

What kind of switch should be on the pump I buy?

There are basically three types of float switches: Tethered, vertical, electronic. The tethered style float switch is great for larger diameter, deeper sump pits. They allow the pump to be off longer between pump cycles so the motor can cool off more completely. At startup, the motor builds a lot of heat so having it be off longer between pump cycles allows it to cool more thoroughly. This can help the pump live longer and lower your overall power usage & costs.

The vertical style switch is great if you have a sump pit that is too narrow and/or too shallow for a tethered style float switch. It is going to operate the pump more often but will not allow the water to get too deep.

An electronic float switch has no moving parts and will take up a lot less space. It is perfect for a small sump pit and often includes options like a built-in water depth alarm, etc. Do not use an electronic float switch if the sump pit receives water from a laundry or wash sink as the soap can coat the electrodes causing it to malfunction. Likewise, soap scum can accumulate on the rod of a vertical style switch and cause sticking of the float.

How much horsepower do I need?

Horsepower basically does two things when choosing a pump: It moves the water out faster, and it (usually) uses more electricity. So there is a trade-off to be considered. If your sump pit fills up rapidly and you have a definite water problem, a higher horsepower pump is needed. In order to keep ahead of the incoming water and keep your basement dry, the higher horsepower pump can pump out the water before it can back up and overflow your sump pit. If you have such a water problem and you need a higher horsepower pump, it is best to increase the size of your sump pit (whenever possible) so that the pump does not have to run as often.

Should I get a cast iron or thermoplastic pump?

Both types of pump are designed for long life and high performance. Which type you choose is largely personal preference. The cast iron pumps are, naturally, a bit physically stronger if that is something that might be needed for your particular installation.

How big should my sump pit be?

When it comes to sump pits, "bigger is better" is somewhat true. You want to have a sump pit large enough to use a pump with a tethered float switch. That allows a reasonable amount of water to accumulate before the pump has to run. The longer "off" time between pump cycles allows the pump to cool off more completely between pumping cycles. Keeping the pump cooler usually results in longer pump life.

Is it OK for my pump to pump out my water softener discharge?

In most cases the pump is NOT designed for that. The high salt content of water softener discharge is very corrosive and will attack the seals, the screws, and even the motor shaft. Salt can even damage many types of stainless steel. It is recommended that you find an alternate place for the water softener discharge.

Is it OK to dump the laundry water discharge into the sump pit?

Most sump pumps are designed for clear, clean ground water. The chemicals in laundry discharge can attack the seals on a sump pump. It's possible for lint and other things discharged to get stuck in the impeller area and jam up the pump. Additionally, the soap scum that can be left behind from laundry water can foul the switch - this is particularly true of vertical switches. We recommend you purchase an effluent pump if you need to pump out laundry water.

Which sump pump type is better: Submersible or Column (Pedestal)?

Both types of pumps are good. In many cases, the motors on pedestal pumps operate with less amp draw. This can make them more economical to run. Pedestal pump motors are cooled by air flow around them while submersible pumps are cooled by the cool ground water they sit in. Your particular installation may impact the cooling of the pump if you need to install the pump in a very tight area, for example, there may not be sufficient air flow or volume to cool a pedestal pump.

What's a check valve? Do I need one?

The short answer here is "Usually- yes." A check valve is a one-way valve. It gets installed in the discharge pipe of your sump pump. When the pump runs, the water is forced out through the valve. When the pump shuts off, gravity wants the water in the discharge pipe to fall back into the sump pit. The check valve prevents that from happening. This prevents the pump from having to re-pump water that it has already pumped out. In the long run, this should extend the life of the pump and save you electricity.

My power outlet is too far away from the sump pit. Can I use an extension cord?

We very strongly recommend that you NOT use an extension cord. It is MUCH better to plug the pump into a dedicated outlet that is fed by a circuit breaker or fuse that feeds power ONLY to that outlet. This ensures that the pump will receive proper voltage. If there is no outlet near the sump pit, we recommend you have one installed there by a professional electrician.

How long should my sump pump last?

This is almost impossible to answer. It's much like asking how long your sofa, your sink, or your car will last. It simply depends too much on how often the pump has to run. If you have a small sump pit, and you have a lot of ground water in your area, the pump may have to run several times per hour. Naturally, that pump is not going to last as long as the same pump in the home of someone with a large sump pit and very little ground water where the pump only has to run a few times a year.

Choosing a pump that is properly sized to your ground water conditions, has the appropriate float switch for your sump pit, and has good electrical supply connected to it will ensure the longest possible life for your pump.

Can I use a sump pump for my waterfall, koi pond, or garden pond aeration?

No. Sump pumps are designed for short periods of operation. Running a sump pump for too long can cause the pump to overheat. It is also oil-filled. If fish waste attacks the pump seals, or it overheats, that oil can be discharged into your water feature. That will kill the fish and plants. When it cools, it will draw water up inside the pump motor which will kill the pump. Using a sump pump any place where water recirculates is not recommended and will void the warranty.


Peace of mind starts with a Pentair pump

For more than 70 years, families have relied on Pentair residential water solutions to move and store life’s precious resource throughout the home.

Our goal is to provide you with essential confidence to weather the storm knowing you are equipped with the right sump pump to protect your home.


Pump troubles?

Whether your sump pump keeps running for a long time or isn't turning on at all, our sump pump troubleshooting guide is designed to help you identify the most likely causes of pump problems and how to fix them.