Facebook Pixel

Rainwater Pumps Buying Guide

If you want to distribute your collected rainwater then you will need to purchase a rainwater pump as part of your rainwater harvesting system. You may be wondering

Which Rain Water Pump Should I Buy?

Installing a water pump will allow you to:

  • Use a hose for garden watering
  • Use a garden irrigation kit 
  • Use rainwater to fill ponds
  • Use rainwater for garden water features
  • Use rainwater to power domestic appliances. 

Rainwater Solutions offer a range of

Which Rain Water Pump Should I Buy?

In this document we will help you to understand how each of them work and with which types of systems they are suited to.

Most domestic operated pumps will be operated by the single phase electric supply, this will ultimately limit the size of pump you can use.

Selecting the right water pump system for you depends on the flow rate, height and distance the water is to be pumped. The following options are available when choosing the right type of water pump to meet your needs.

Which Rain Water Pump Should I Buy? Understanding Pump Terminology:

Single Stage Pumps

A single stage pump has just one impeller that will provide a fixed volume and pressure of rainwater from the output. Single stage pumps have a limited amount of head development at any given flow rate. A single stage pump is suitable as long as you don’t need to pump large flows at high pressure. Our self-priming

Multi-stage Pump

A simple way to understand a multistage pump is as a series of single stage pumps all mounted on one shaft with a single large case that holds all of them. Multi-stage pumps (also known as Centrifugal Pumps) are commonly used when you have to pump large flow rates at high pressure to overcome gravity. Multistage pumps can be either horizontal or vertical in configuration.

As with all centrifugal pumps, the capacity of any single stage varies with the amount of head (discharge pressure) that stage develops. More head, less flow. Less head, more flow.  To produce more head, multiple stages are operated in series so that each stage's head is added to that of the previous stage.

Flow Rate & Head

On every single water pump, flow rate and pump head are the two most important specifications. Flow rate is how much water can be moved in time period without any restriction. This value is usually given in gallons per hour (GPH), liters per hour (LPH). A benchmarking procedure would be simply to see how much water can be moved from one tank to another in a hour. Head is how high or hard water can be pushed at full load. This value is usually given in feet or meters. A benchmarking test would be to see high the pump can push water in a thin vertical tube.

Submersible Water Butt Pumps

In submersible applications, the impeller is surrounded by enough water to create the pressure differential and thus to pump water.

Submersible water pumps can operate fully submerged within the water storage tank. The pumps are available in single or multi stage versions when higher pressures are required. Our submersible water pumps are often used within the garden to create water features such as fountains and ornamental ponds. For these requirements, they combine with our rainwater harvesting system, diverters, water butts and irrigration systems perfectly. 

The main advantage of this type of pump is that it prevents pump cavitation, a problem associated with a high elevation difference between pump and the fluid surface. Submersible pumps push rainwater to the surface as opposed to self-priming pumps which pulls the rainwater.

Self-Priming Water Butt Pumps

The term "self-priming pump" describes a centrifugal pump that can use an air-water mixture to reach a fully-primed pumping condition.  A "self-priming" centrifugal pump overcomes the problem of air binding by mixing air with water to create a fluid with pumping properties much like those of regular water. The pump then gets rid of the air and moves water only, just like a standard centrifugal pump.

Self-priming pumps cannot operate without water in the casing, therefore it will not work in your water butt or tank has no or low levels of water in it.

A self-priming pump is ideal if you want to install the pump on top of the water butt or away from where the rain water harvesting tank is located. This pump will automatically prime and then it resumes water pumping.

Centrifugal / End-Suction Water Butt Pumps

A centrifugal pump is any pump that uses centrifugal force to create a pressure differential in a fluid, thus resulting in pumping action.

A centrifugal pump that has a casing with the suction coming in one end and the discharge coming out the top. They are almost always single stage pumps.

A popular pump widely used when the suction port of the pump is always below the surface level of the water.

Need more?

If you can’t see the pump you’re looking for or need advice, please contact us  and we'll do our best to find the best solution for you and your budget.

Show our range of pumps by clicking here.


©Copyright 2021 - Rainwater Solutions is a trading name of GM8 Group Ltd. A company registered in England & Wales (company number 04414980)