Most rainwater harvesting systems require pumps to transfer the water from storage tanks to the point of use.
Submersible pumps are generally more efficient than suction pumps and do not suffer with the same limitations. They are also effectively silent as they are situated within the tank, which itself is (usually) below ground and external to the building.
Rainwater harvesting systems can be used in both domestic and commercial settings. Rainwater harvesting basically involves collecting the rainwater that falls on your building and on your land and using it in your toilets, garden taps and washing machines. Most rainwater harvesting systems use a system of rainwater harvesting equipment, tanks, pipes and pumps located either above or below ground. Two main manufacturers Hydroforce and Diverton make Rainwater harvesting pumps. The pumps can be used above or below ground and submersible pumps are also available.
In a domestic rainwater harvesting system a tank is placed either above or below ground and then the rainwater is collected via a system of guttering and pipes, filtered, stored and then pumped back to where you wish to use it. The rainwater harvesting system can be either a gravity or direct feed system. In a gravity feed system the collected water is pumped into a tank in the loft of your house that then uses gravity to deliver the water to your taps, washing machine or toilets. In a direct feed system the pump pumps water directly from the collection tank to the toilets, taps and washing machine.
Commercial rainwater harvesting systems generally use the same principals as domestic systems with larger storage tanks, more powerful pumps and can pump the water up to a head of 300 meters, useful in multi storey buildings. Pumps can be run using solar power and installing a rainwater harvesting system can save a company water and energy.
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 irrigation 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.
