Should You Choose an External or Submersible Water Tank Pump?

If you are plumbing rainwater into your home, then you will need a water pressure pump to ensure your tank water gets to where it is needed. Many go for an external water pump, however submersible pumps which are installed inside your tank are becoming more popular. This article explores the benefits each provide and reasons for preferring one to the other.

External Pressure Pumps

External pressure pumps (also known as above ground pumps or surface pumps) are the most common type of pump purchased when plumbing in rainwater. It is positioned outside the tank, normally beside it in a weather safe location.

Optional tank covers which come in a range of colours can be purchased for external pumps. Tank covers can protect your pump from weather, reduce the noise of your pump, and often look nicer than seeing an exposed pump beside your tank.

Submersible (In-Tank) Pumps

Submersible tank pumps (also known as an in-tank pump) is, as the name suggests, placed inside your rainwater tank. They are normally designed to pump water upwards through a pipe that goes to the top of your tank. It is there a rainwater-to-mains water device can be installed, and the necessary pipework is attached to connect the rainwater to your plumbing.

Pump Advantages and Disadvantages

To help you weigh up with water pressure pump is for you, we have identified five consideration points:

  1. Price – a submersible pump is more expensive to buy since it needs required waterproof casing, however if buying an external pump you might also need to buy an additional outlet fitting, valve, flexible hose connection and pump cover.
  2. Noise levels – a main advantage to submersible pumps is that they are very quiet. This is because the water they are submerged within and tank walls block most of the pump noise. External water pumps can be very noisy, even those that claim to be quiet.
  3. Energy Efficiency – external water pumps need to be able to suck water in, whereas submersible pumps are surrounded in water and so only need to focus on pressurising water out. Submersible pumps are therefore relatively less complex and more energy efficient.
  4. Maintenance – if your external pump requires maintenance then they are easy to access. Submersible pumps however are located inside your tank, and so some dismantling is required before accessing your pump. Submersible pumps also have waterproof seals, meaning if any repair work is performed, there is some risk it may not be appropriately sealed (although the repair person should guarantee their work).
  5. Tank Water Space – while a submersible pump won’t displace too much water, it will result in around 50 litres less rainwater being stored in your water tank.

I find many do not realise water pump options exist that go inside a tank. So I hope this article have found this article helpful in evaluating whether a submersible pump is preferable to an external pump option. If you like this article, please share it. Feel free to comment below should you have anything to add or unanswered questions.

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