A 1,000-litre tank can store a large amount of rainwater, but you still need to be able to use it easily.
To fill a watering can placed just below the tank, a pump is not always necessary. However, to supply a garden hose, sprinkler or several points of use, a pump often becomes essential.
The choice mainly depends on the intended use, the required pressure and the distance between the tank and the point of use.
When is a pump necessary?
A pump is useful whenever water needs to be transported with sufficient flow and pressure.
It may be necessary for:
- using a garden hose
- supplying a sprinkler
- setting up a drip irrigation system
- sending water several metres away from the tank
- supplying several points of use
For a simple garden watering system, a rainwater harvesting tank can therefore be combined with a pump suited to your needs.
When can gravity be enough?
If the point of use is located below the water level in the tank, gravity may allow the water to flow without a pump.
This is particularly suitable for filling a watering can or bucket directly from the tap.
However, this solution provides limited pressure. A tap does not create pressure on its own: the flow rate depends on factors such as the available water height, pipe diameter and pressure losses within the system.
For a fairly long garden hose or a sprinkler, gravity is therefore often insufficient.
Submersible pump or surface pump?
Two main types of pump can be used with a 1,000-litre tank.
The submersible pump
A submersible pump is placed directly in the water.
It draws water from inside the tank and sends it to the irrigation system.
Its main advantages include:
- a relatively discreet installation
- few priming problems
- operation generally well suited to rainwater harvesting tanks
However, it is less convenient to access for maintenance or replacement.
The surface pump
A surface pump is installed outside the tank.
It draws water through a hose connected to the tank.
It is easier to inspect and maintain, but the installation must be correctly sized to avoid suction or priming problems.
It must also be protected from bad weather and frost.
What is a booster pump used for?
A booster pump system generally combines a pump with equipment designed to maintain a certain pressure within the network.
This solution becomes useful when several points need to be supplied or when you want performance closer to that of a conventional water supply system.
For simply filling a watering can, this type of equipment is generally unnecessary.
However, it can be useful for several hoses, an automatic irrigation system or multiple points of use around the garden.
Which pump should you choose for each use?
The right choice depends above all on what you want to do with the stored water.
For filling a watering can
A pump is generally not necessary if a tap is installed low enough.
Gravity may be sufficient.
Containers Service offers various taps for 1,000-litre tanks, with several connection types available.
For a garden hose
A pump is often preferable.
It provides a more consistent flow rate and greater pressure, especially when the hose is long.
A submersible pump or surface pump may be suitable depending on the setup.
For drip irrigation
Drip irrigation systems generally operate at relatively low pressure.
However, a pump may still be necessary if the tank is far from the irrigation system or if several lines need to be supplied.
The main thing is to ensure that the pressure remains compatible with the system being used.
For a sprinkler
A sprinkler requires more pressure than simple gravity-fed water flow.
The pump should therefore be selected according to the flow rate and pressure required for the sprinkler to operate correctly.
For several points of use
If several hoses or pieces of equipment need to operate at the same time, you need a pump capable of providing sufficient flow.
A booster pump system may also be useful if you want to maintain consistent pressure.
What criteria should you consider when choosing a pump?
Power alone is not enough to determine whether a pump is suitable.
Several characteristics need to be considered.
Flow rate
Flow rate refers to the amount of water the pump can deliver over a given period of time.
Several points being used simultaneously require a higher flow rate than a single garden hose.
Pressure
Pressure determines, among other things, the pump’s ability to supply a hose, spray nozzle or sprinkler.
Pressure that is too low may make some equipment ineffective.
Conversely, pressure that is too high may be unsuitable for some drip irrigation systems.
Delivery head
The delivery head indicates how high the pump can send the water.
It must take into account not only the difference in height, but also losses caused by pipes, bends and fittings.
The distance between the tank and the point of use
The farther the water has to travel, the greater the pressure losses may become.
A pump that is sufficient for a tap located a few metres away may therefore be less suitable for a sprinkler positioned much farther away.
Why is pipe diameter important?
Pipe diameter directly affects flow rate and pressure losses.
A pipe that is too narrow or too long can significantly reduce pump performance.
It is therefore important to choose pipes and fittings that are suitable for the installation.
To connect one or more tanks, various connection kits for 1,000-litre tanks may include suitable pipes, fittings, valves and seals.
What equipment should be installed around the pump?
The pump is only one part of the installation.
Several additional components should also be considered.
Filtration
A filter helps prevent leaves and debris from entering the tank and pump.
This reduces the risk of blockages and makes maintenance easier.
Fittings
The fittings must match the tank outlet, the pipe diameter and the pump inlet.
It is best to avoid overly restrictive fittings, as they can reduce the flow rate.
Taps and valves
A tap provides a simple water draw-off point.
A valve, on the other hand, allows part of the installation to be isolated for maintenance.
1,000-litre tanks are generally equipped with a drain valve and can be fitted with various connection accessories.
The overflow
The overflow must remain functional even when a pump is installed.
When the tank is full, excess water must be able to drain away correctly without causing overflow around the tank.
Protecting the pump against dry running
A pump should not continue to operate when the tank is empty.
Depending on the model and installation, dry-run protection may therefore be useful.
It stops the pump when the water level becomes too low.
This safety feature is particularly useful when the pump operates automatically or when the tank’s water level is not easily visible.
Common mistakes when choosing a pump
Some mistakes can result in insufficient flow or inefficient operation.
In particular, avoid:
- choosing a pump based only on its advertised power
- overlooking the required pressure
- forgetting to take pipe length into account
- using pipes with too small a diameter
- using too many restrictive fittings
- failing to provide filtration
- running the pump when the tank is empty
- choosing an oversized pump for a very simple requirement
It is better to start with the actual intended use and then size the pump and pipes accordingly.
In summary
For a 1,000-litre tank, the pump should primarily be chosen according to the intended use.
For filling a watering can, gravity may be sufficient. For a garden hose or simple irrigation system, a submersible or surface pump may be suitable. For several points of use or a need for more consistent pressure, a booster pump system may be more appropriate.
Flow rate, pressure, delivery head, distance and pipe diameter are just as important as the type of pump.
Finally, an efficient installation does not rely on the pump alone: filtration, fittings, taps, pipes, overflow and dry-run protection should also be taken into account.
