Submersible Water Pumps: Your Buying Guide

May 23, 2025 | Nate Cord

Got water that needs moving, whether it be from a flooded basement, a garden pond, or a deep well? A submersible water pump might just be exactly what you need.

But with so many types and models out there, figuring out which one is right for you can feel a bit overwhelming, especially if this is your first time dealing with one. But that’s where we come in.

In this comprehensive buying guide, we’ll break down everything you need to know about submersible pumps in plain, simple terms.

Plus, our team of experts have hand-picked some of the best pumps on the market to help make your decision that little bit easier.

So, let’s start with the basics…

What Is a Submersible Water Pump​?

A submersible water pump is one of the most commonly used water pumps out there, designed to operate while fully submerged in water or another fluid.

They can be used for a wide range of tasks, from draining flooded areas to irrigating gardens, and work by pushing water rather than sucking it, which offers a more efficient and effective operation.

What Is Submersible Pump Used For​?

The submersible pump is used for draining water or other fluids from one place to another by being fully submerged in the liquid it is pumping.

These pumps are especially useful in situations where water needs to be drained, lifted, or circulated, and are designed to work while being completely underwater (hence the name ‘submersible’).

There are a variety of different models of submersible water pumps on the market, and each one is designed for a specific type of water.

For example, clean-water submersible pumps are designed for clear or slightly contaminated water that doesn’t contain debris or solids, and are typically used in domestic or light-duty applications like draining swimming pools or circulating water in ponds.

You’ll also find dirty-water submersible pumps which are built to handle water that contains small debris, sand, or mud, making them ideal for more rugged conditions like draining flooded areas (basements, garages) or construction site dewatering.

Sewage submersible pumps on the other hand are heavy-duty pumps designed specifically to transport wastewater and raw sewage, including liquids mixed with solid waste. They are essential in situations such as septic tank systems, sewage treatment plants and residential and commercial plumbing systems.

You can browse our range of submersible pumps here from Sealy, all of which are simple to install and operate. And if you have any questions for our experts, feel free to give us a call on 01639 849847.

How Does a Submersible Water Pump Work​?

As touched on briefly above, a submersible water pump works by being placed directly in the water it needs to move.

Once it’s turned on, it uses an electric motor to pull water in through an intake and push it out through a pipe or hose. Because the whole thing is underwater, it doesn’t need to be primed like other water pumps – it just starts working right away, quietly and efficiently.

Some submersible pumps come with a float switch, which is really useful if you want the pump to turn on and off automatically. But if you need to drain an area completely dry, you’ll have to do that part manually. If this is the case, just make sure to switch the pump off in time so it doesn’t run dry and get damaged.

Some models of submersible water pumps give you both options – manual and automatic – which is super handy.

How to Choose the Right Submersible Water Pump

Choosing the right submersible pump is a super important decision, and it all really comes down to what you need it for. Here are a few key things to consider when looking around:

1. What Kind of Water Are You Dealing With?

We went into this further up in the blog, so you’ll know that the type of water is an essential factor when it comes to choosing the right type of submersible water pump.

To recap: if you’re just moving clear water (like from a pool or tank), a simple clean-water pump will do the job. For dirty water i.e. floodwater, mud, or stuff with small debris, you’ll want a dirty-water pump. And if you’re dealing with waste or larger solids, go for a sewage pump or one with a grinder.

2. How Much Water Are You Needing to Move?

Another important thing to think about is how much water you actually need to move.

That’s where the flow rate comes in, which tells you how much water the pump can handle, usually measured in liters per minute or gallons per hour.

Typically speaking, if you’re just emptying a small pond or a water tank, a lower flow rate is probably fine. But if you’re dealing with something bigger, like a flooded basement or a large well, you’ll want a pump that can move a lot more water quickly (otherwise you risk the job taking forever).

On the flip side, getting a super high-powered pump for a tiny job will just be a waste of energy. So it’s really about finding the right balance for what you’re trying to do.

3. How High or Deep Do You Need to Pump It?

Another important consideration is how high or deep you need to pump it. And this is where something called head height comes in (i.e.how far the pump needs to push the water).

If you’re pumping water up from a deep well or trying to send it up a slope, you need a pump that can handle that extra distance. Not all pumps are built the same, so if the pump can’t push water high enough, it won’t do you much good.

We recommend that you always check the maximum head height listed in the pump’s specs…it’ll save you a lot of frustration later.

4. Do You Want It to Turn On and Off by Itself?

If you want it to start and stop automatically as the water level changes, look for a pump with a float switch (as we touched on further up).

This little device acts like the pump’s on/off switch and responds to the water level. For example, when the water rises, the float goes up and kicks the pump on. When the water drops back down, the float lowers and shuts it off.

This feature is handy if you’re dealing with something like a sump pit or flood-prone area, where the water level changes on its own. Another great benefit is that it helps protect the pump, since it won’t run dry or keep running when there’s no water left to move.

What is the Best Submersible Water Pump On the Market?

Our water pump experts have hand selected two of the, (in our opinion), best submersible water pumps on the market, for both clean and dirty water applications.

Sealey 250L/min Automatic Submersible Clean Water Pump

The Sealey 250L/min Automatic Submersible Water Pump is a great example of a quality clean water pump. Constructed with corrosion-resistant materials, it features a stainless steel motor case and a Noryl base cover, ensuring durability and longevity.

With a powerful 900W motor, this pump delivers a maximum output of 250 liters per minute and can handle a maximum head height of 9.5 meters, making it suitable for tasks like draining cellars, sinks, cisterns, baths, and general water transfer.’’

Sealey 133L/min Automatic Submersible Dirty Water Pump

When it comes to dirty water, the Sealey 133L/min Automatic Submersible Dirty Water Pump is a solid choice. Built to tackle challenging drainage tasks, this pump is ideal for clearing out flooded basements, construction sites, or any area with murky water.

With a flow rate of 133 litres per minute and a maximum head height of 5 metres, it efficiently moves water containing particles up to 30mm in size.

What’s more, the pump is equipped with an automatic float switch, which activates when water levels rise and shuts off as they drop, preventing dry running.

It also operates in water as shallow as 40mm and can be submerged up to 7 metres, making it versatile for various applications.

There we have it! Do you have another question or require additional advice on water pumps, generators or garden machinery? Check out our regularly updated blog page, or don’t hesitate to get in contact with our experts using this form or via phone at +441639849847.

At Generators Direct, all of our products are manufactured, tested and certified to industry standards and come with a price promise – you won’t find prices cheaper anywhere on the web, but if you do, we’ll match them. In addition to this, all orders come with free mainland UK shipping and after-sales support from our experts.