Irrigation takes up an enormous proportion of the gardening work that needs to be done. A cistern allows you to use rainwater for irrigation. However, the pump used should meet certain requirements.

In a nutshell

  • From a technical point of view, rainwater counts as gray or even dirty water because of the foreign substances it contains
  • the centrifugal pump has now established itself as the state of the art for rainwater
  • Suction pumps can be set up protected next to the cistern
  • Submersible pumps are very flexible, but cannot remain in the water permanently

Pump requirements

In order to determine which pump is ideally suited for your cistern and precisely for your application, you should first realize what requirements are placed on the device by the specific form of use:

Source: Hans Haase, Kunststoffcisterne IMG 20220714 120822174, edited by Plantopedia, CC BY-SA 4.0
  • Safe functionality with contaminated (rain) water
  • Insensitivity to algae etc.
  • Resistance to temperature changes and atmospheric agents
  • Protection of all components against moisture (including connection cables, etc.), such as fog, rain, soil moisture
  • Compatibility with common hose and pipe systems for garden irrigation

Which model is ideal?

Once it is clear what a pump for garden irrigation using a cistern must be able to do, the essential question arises as to which models meet the requirements.

Notice: There are countless models of pumps with the necessary suitability on the market. Ultimately, however, these models can be traced back to a few functional principles. The list is thus manageable and easy to master even for laypeople.

The centrifugal pump

Before looking at the actual pump types, we will look at the technical functional principle of pressure generation. A functional structure is used here for almost all pumps suitable for garden irrigation: the so-called centrifugal pump.

functionality

An axially mounted impeller rotates and generates the required pressure via the impeller blades. Depending on the size of the blades and the entire impeller and the free spaces provided between the impeller and the housing, this technology is able to transport even larger dirt and foreign bodies without causing damage.

Strengths and weaknesses

This design convinces with smooth running and thus a long service life. At the same time, a high flow rate is achieved, which can also contain contaminated water along with solid bodies. With a simple design, it is particularly low-maintenance and easy to eliminate. However, such a pump is only able to draw in water on its own to a limited extent. Either the system has to be filled with water from the pump once before it is put into operation, or the suction path is at least limited in terms of length.

One mode of operation - several types

Based on the technology of the centrifugal pump, at least two proven and widely used types of pumps suitable for garden irrigation have emerged:

The pressure pump

A widely used type of pump is the pressure pump. Usually placed free-standing, it has two connections: an inlet for the water to be pumped and an outlet for the discharge of the water. This pump is usually placed in an existing pipe connection between the cistern and the extraction point and combines a suction with a pressure function. Coming from the reservoir, the water is sucked in. From the outlet of the device, the transport takes place via the pressure generated. A first pre-filtering against dirt and foreign matter usually takes place directly at the inlet to the suction hose, where a sieve or a so-called "catcher" is installed, for example.

Benefits:

  • fixed installation possible
  • high conveying capacity
  • no special precautions (e.g. particularly large access opening) on the cistern necessary
  • Easy inspection due to easily accessible installation locations
  • no special technical requirements for sealing etc. of motor and power supply

Disadvantage:

  • high effort when setting up and changing location
  • high demand for accessories with suction and pressure hoses

The submersible pump

A submersible pump is a special type of dirty water pump. It is not set up next to the cistern or between the water reservoir and the place of delivery. Instead, the entire pump technology is hung on a rope directly in the water to be pumped or placed on the tank floor. All that is then required is a pressure hose leading away from the unit in order to actually transport the water to the desired point of consumption.

Benefits:

  • easy and quick to move
  • no complex suction hoses necessary
  • Due to its location directly in the water, no filling is necessary
  • very low noise development due to the noise-dampening effect of the water

Disadvantage:

  • Size and capacity limited due to handling when hanging in the tank
  • complete removal necessary for revision or repair
  • correspondingly large access to the cistern required
  • if left permanently in the water reservoir, there is a risk of rapid algae growth and contamination

The handle pump

Finally, a variant without a motor should be briefly presented at this point: the handle pump. Contrary to the other motor-driven models, this is not a centrifugal pump, but a piston pump. Comparable to an air pump, with every movement of the pump arm, a filling of the piston attached underneath is transported. With the counter-movement, the piston fills up again and the process starts again. The location must be chosen directly above the cistern, as the standpipe of the pump pointing downwards must point directly into the water.

Notice: This technique can be found in the vast majority of hand-operated water pumps. With proper maintenance, it is almost indestructible. Some models have been in operation for well over 100 years.

Benefits:

  • no electrical connection required
  • environmentally friendly as it is emission-free
  • very robust and low-maintenance

Disadvantage:

  • high cost of delivery
  • simple displacement is not possible
  • no automated operation possible

frequently asked Questions

Why can't I use any other pump technology for garden irrigation?

Of course, membrane pumps for pumping water in the garden also work with the appropriate filters. However, these devices suffer far more quickly from dirt and algae formation. In addition, their conveying capacity is comparatively low.

Are there also motorized piston pumps?

Among the existing pumps, there are certainly still isolated pumps that use piston technology. On the other hand, this type of construction is no longer found in current models, since the large number of mechanical components would be too expensive and would entail too much maintenance.

What performance should pumps for garden irrigation have?

The most interesting thing is certainly how much water a device can transport per minute. However, this value also depends on the hoses used, the delivery height and distance. Therefore, the only way to narrow down the dimension is to look at the motor power: Common pumps for garden use are usually between 2,000 and 4,000 watts.

Category:

Garden maintenance