ᐅ Garden Irrigation Using a Rainwater Harvesting Tank

Created on: 2 Jul 2020 08:27
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Kuota88
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Kuota88
2 Jul 2020 08:27
Hello everyone,

The new build hasn’t even started yet, but early planning never hurts.

We will be installing a rainwater cistern underground, from which we want to run an automatic garden irrigation system. Now we need to decide with the builder where to place our outdoor water tap points on the house (two in total). One should be located near the cistern.

Is there a pump that can be connected to both the cistern and the mains water supply, and automatically switch over when the cistern is empty? Or how is this usually done?

Also, would you recommend installing a submersible pump inside the cistern, or using an external pump placed in the garden to draw water through a hose?

Best regards
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pagoni2020
2 Jul 2020 16:41
This topic was discussed here exactly a few weeks ago. You just have to search for it. I would size the cistern large enough, depending on your needs, around 4,000–6,000 liters (1,050–1,585 gallons), and use a simple domestic water pump with a suction line.

After that, you can bury a simple hose slightly along the edge and place it where you want it.

With a domestic water system, you have constant pressure; this should be somewhat installed properly considering electricity, frost, etc.

I would definitely keep both lines separate, otherwise it becomes unnecessarily complicated and expensive. There are thousands of tools, but I would keep it simple.
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Kuota88
3 Jul 2020 07:50
Thank you! I will look for the thread.

So, you would connect the Gardena pump, for example, to the domestic water system? Both are located near the cistern, which means I would need two power outlets there.
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bortel
3 Jul 2020 10:05
Forget 6000 liters (1600 gallons), that’s absolutely nothing... whenever you need it, it will be empty.
I have just under 9000 liters (2400 gallons)...
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Kuota88
3 Jul 2020 10:07
We are planning for 10,000, with 3,000 allocated as retention volume. Would you recommend going even larger in that case?
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dab_dab
3 Jul 2020 10:31
This cannot be answered with a general statement. Make a proper sizing based on your roof areas, the garden area to be irrigated, and any other planned consumers. Various manufacturers offer tools for this, and a reliable supplier will be happy to assist you.

In your case, a Retentions Plus system would be suitable.

That way, you get a solid figure, and you can always upscale from there.