Submersible Sump Pump Buying Guide 2021

If you’re not technically minded, don’t know a huge amount about DIY and home repairs or simply aren’t that interested, buying a Sump Pump can be a difficult process. You’re immediately confronted with a lot of different choices and even technical terms you may not know the meaning of. This is intimidating for anyone.

Sump pumps can be used in industry. For instance, wells and other forms of drainage, but generally the consumer market for sump pumps involves those to stop flooding within your home.

We’ve simplified the process with our guide to buying submersible sump pumps, answering all the questions you could have and leaving you ready to decide if a submersible sump pump is for you, and if so, which model and features you are going to need.

What is a Submersible Sump Pump?

Submersible Sump Pump

As you probably already know, a sump pump is a piece of equipment which sits in a pit usually situated within a basement. This is called a ‘sump pit’. The sump pit is in place for the purpose of accumulating any water and other liquids, and then the pump’s job is to pump them up and out of your home, avoiding flooding.

Sump pumps can either sit in the sump pit or above it. Those which sit inside are called submersible sump pumps, and are what we are focusing on here. The alternative is called a pedestal sump pump as this sits next to the pit and is above the level of the pit.

How A Submersible Sump Pump Works

Submersible pumps have a waterproof casing, or at least their motor does. This means that there are no issues with it being totally underwater. They work in a slightly different way to pedestal pumps (more on this later) but generally do the same job.

Submersible Sump Pump Works

The sump pump contains a sensor which detects when water reaches a certain level. This is very similar to what you may have in a toilet to ensure that it doesn’t overflow when water is coming in.

The sensor will activate only when a certain level of water is hit. In the case of heavy rain, the pit will gradually fill up and the sensor will be able to then trigger the pump motor when it needs to. The motor uses a rotor blade which is designed to force the liquid out of the pit. The water is then carried through a pipe or a hose up and out of the pit, and out of the basement or wherever it is fitted.

Features to Consider

Naturally, not all sump pumps are created equal! There are a few distinguishing features to consider along with the build quality of a submersible pump. Below are many of the criteria which will help you make your buying decision.


Submersible Sump Pump Switch

The switch is the mechanism which triggers the pump starting based on the water level. There are different types of switch available:

  • Vertical float switch. This simply goes up and down with the water. Imagine a floating ball which bobs on top of the water, when it reaches a predetermined level then the switch comes on and the pump starts to work. As it is a simple mechanism, it doesn’t get stuck very often and is quite reliable.
  • Tethered float. This type is the most common within the home, but is found in pedestal sump pumps more often than other types. The float can get caught in things and has been known to sink. Realistically, if using a tethered float in your sump pump, it needs to be submerged within a pit that is at least 14 inches in diameter to ensure it doesn’t catch and cause issues.
  • Electrical switch. This doesn’t use the water in the conventional way to trigger a switch. An electrical switch relies on water pressure to signal when the pump needs to start working.


I know you’re not buying a car, but horsepower is the unit of measurement for these types of pumps, too. Instead of being high numbers though, your average home sump pump is usually somewhere between 1/6th and ½ horsepower.

How much horsepower you require comes down to the size of the area, and the likelihood of a lot of water entering quickly.

If you are prone to flash flooding, or somewhere the water needs to be pumped a large distance, then you may need one of the more powerful pumps (½ horsepower, for instance) to ensure that you can quickly get the water away from anywhere it can cause danger. It is usually safer to have more power, and really, the models which are advertised as having ⅙ horsepower or similar are only useful if you are very occasionally having to use the pump.

Pumping Capacity or Gallons Per Hour

This is arguably more important than the measurement of horsepower. You will see this listed as the GPH of your pump, or you may see it listed as GPM (gallons per minute). This is, as you may have guessed, simply the measurement of how many gallons the pump can shift in a certain time period.

The reading will often display as something like 2400 GPH. Every sump pump will have this measurement listed on the product description, as it is such a vital aspect of the buying decision. There is no point installing a sump pump which can’t keep up with the water it is likely to be exposed to.

The gallons per hour can also be affected by the size of the pit and the distance which it has to pump. This is worth considering, and reading reviews on each individual model can help you to work out how reliably it can pump under all conditions.

Housing Materials

Submersible Sump Pump Housing Materials

The housing materials are always an important consideration for this type of product, but even more so when you consider that a submersible pump can be subjected to a fair amount of time underwater. Many different materials when subjected to water can become damaged, and cheap and flimsy materials and metal don’t last long. Choosing the right materials is vital to ensure your pump lasts.

Cast bronze, steel and cast-iron are popular and often combined with epoxy resin style coating to help minimize the effect of water. Sheet metals such as aluminum are not really very useful in this scenario, they quickly rust and don’t offer protection to the motor. If you’re trying to find an affordable model, be careful to ensure the materials used aren’t going to let you down.

Polypropylene tends to be used within the pump too, almost universally. As you might expect, the better materials used, the higher the price often is. This is just something you’ll have to put up with if you’re looking for a model that is built to last.


One often overlooked aspect of submersible sump pumps is the power supply. As they are in close contact with water, the power supply is made specifically to ensure safety. You can not use an extension cord with a submersible sump pump. This means you simply have to ensure you have enough length to reach a power supply when you purchase, or end up having to send the pump back.

Pros and Cons of Submersible Sump Pumps

There are some choices to be made here, and naturally this means pros and cons. Weighing these up will help you to decide which pump is for you, or even if a submersible sump pump is the correct type for your basement.


  • Due to operating under the water, noise level is much lower than other types of pump, meaning no disturbing noise coming from the basement.
  • Water also automatically helps to cool down the motor during use, just like your computer has a cooling device inbuilt. This ensures it is effective and unlikely to stop working even when it is having to work hard.
  • Submersible sump pumps can often generate more power than pedestal style pumps making them more effective at lifting water up and away to a suitable point.
  • They don’t get in the way of other appliances you wish to have in your basement, due to being kept within the sump pit.


  • Submersible sump pumps can be more expensive than the pedestal alternatives.
  • Due to being underwater they may not last as long (you can still often get 20 years or more of use out of a pump however).
  • Any future repairs may be more expensive as they can involve ripping up floor within your basement to access the pit.
  • Any future repairs may be more expensive as they can involve ripping up floor within your basement to access the pit.

Backup Systems

Submersible Sump Pump Backup Systems

Something we always try to mention here is backup systems. These are usually battery operated systems or water based pumps which automatically kick in when your sump pump isn’t working. Electrical issues and water do not mix, and even though submersible pumps are usually absolutely fine when subjected to water, your power supply might not be. Having a backup system is always recommended.


It can be a confusing world when you’re trying to find sump pumps which are appropriate. Hopefully the information above can help you to inform your decision.

There are many horror stories of people buying pumps with power supplies which aren’t long enough, or buying pumps which didn’t have the right amount of power to clear the water their house was subjected to. A little time researching before making your decision can ensure you get a product which will last rather than something which could be useless to your home.

Leave a Comment