A guide to Submersible Pumps

Submersible pumps are specifically designed so that they can be completely submerged within the liquid which is to be pumped, are completely waterproof and located at the bottom of the wet well containing the water.


[caption id="attachment_54" align="aligncenter" width="444"]Submersible pump with automatic float switch Submersible pump with automatic float switch[/caption]


What are the advantages of submersible pumps?

Submersible pumps are located at the bottom of the wet well, this means they’re capable of lifting water out from much greater depths. Many surface mounted pumps struggle with lifting water greater than 8metres in depth whereas this is no trouble for a submersible pump.

As submersible pumps are fully submerged, the pressure of the water surrounding them prevents air being trapped. As a result all submersible pumps are self-priming.

Water surrounding the pump help to keep it cool and prevents overheating.

Pumps and motors are known to be noisy but once again submersible pumps are a clear winner in this field. Due to the body of water surrounding the pump, this helps eliminate the noise and vibrations.

Submersible pumps are actually very common! Just walking through a retail park or housing estate you might expect to see them, but why don’t you? This is because they’re all underground and hidden from view. Just as well as a nice flowerbed is much better to look at than a pump and pipework!

[caption id="attachment_55" align="aligncenter" width="1024"]Pumping station by the side of a road containing submersible pumps Pump station and control kiosk by the side of a road[/caption]


How do submersible pumps work?

  • There are several ways in which a submersible pump can be operated. Most commonly the pump is controlled via the use of a built-in float switch.
  • As the water level rises it tips the float switch which in turn switches the pump on.
  • The impellor then draws water into the pump and out through the discharge pipework.

[caption id="attachment_50" align="aligncenter" width="500"]Arrows depicting the flow passing around the impeller of a submersible pump Arrows depicting the flow passing the impeller of a submersible pump[/caption]

Submersible pump applications

Pumps are sized depending on how far and how high the liquid needs to be pumped. In many cases you have two or three pumps working together to achieve a higher flow rate. Alternatively, just to have a pump as back up in the event one pump fails. The following types are the most common of applications:

Pumping Sewage – new buildings are often built below the level of the main sewer. In these instances the sewage is collected in a well and then pumped up to the main sewer.

Dewatering – surface water can collect in many unwanted places. Cellars and basements often require sump pumps to remove ground water. In addition to this, many new urban development’s now involve large tarmacked or concreted areas such as car parks. The rain water can then be collected and pumped into a local stream or soakaway.

Irrigation – submersible pumps and borehole pumps are used in farms and gardens for watering crops and are excellent at lifting water from great depths. Submersible pumps are also used in rainwater harvesting tanks to recycle rain water. This is a fantastic way to help save the environment…. and your money!


How much of the pump can be submerged?

All of it, this includes the whole pump and the cable. The only part that cannot be submerged is the plug/exposed end of the cable.

How long can submersible pumps continuously run for?

Submersible pumps can run as long as you need it to but only if your well has enough water to support the pump. Pumps cannot be left running if it is not submerged in water as it will simply overheat and do some serious damage.

How reliable are submersible pumps?

They're well known for their reliability and providing it is sized correctly you can expect to get many years from it. There are instances of submersible pumps lasting 15 years without even being serviced!

How do you lift submersible pumps in and out of a deep well?

Use rope or a metal lifting chain attached to the handle. Do NOT use the power cable to lift it in and out.

Can you use any submersible pumps for sewage?

No, we do however stock both surface and sewage pumps. Sewage pumps are designed to deal with tissue and other flushables.

What type of pipework or hose should you use?

Generally speaking you do not want to use pipework smaller than that of the pumps discharge. If you do this, you are likely to reduce the output of the pump and cause damage to it. As a result, if you have a 2” pump, we recommend using a 2” hose or 2” pipework.