ᐅ Collect rainwater or drill a well?

Good day!

The ongoing dry spell has brought up a topic again that I have postponed several times: Where should the water for garden irrigation come from? Until now, I have been using water from the public supply: always available, consistently good pressure, and fairly cost-effective thanks to separate metering. But it probably isn’t sensible to let high-quality drinking water soak into the garden soil.

Is there a general rule of thumb about which form of garden irrigation is best from both financial and ecological perspectives? Essentially, there are three options: water from the public supply, collecting rainwater from roofs in cisterns, or drilling a well (if permitted).

To make the use of rainwater worthwhile, you would need to store a large volume, at least 20 to 30 cubic meters (700 to 1,060 cubic feet) to cover dry periods. The costs for cisterns and the associated earthworks would accordingly be high. Then there are ongoing expenses, such as electricity and maintenance for the pump. Drilling a well also involves costs, plus electricity and pump maintenance. The advantage of a well is that you don’t have to worry about storage capacity.

My garden irrigation system (drip hoses under mulch) consists of four zones, each of which requires one cubic meter (35 cubic feet) per hour. During prolonged dryness, I would ideally run each zone for one hour every two to three days. That adds up to about ten cubic meters (350 cubic feet) per week. With 30 cubic meters (1,060 cubic feet) of storage, this would last just about three weeks. We are increasingly facing situations in Berlin where it doesn’t rain for well over three weeks.

Has anyone here already worked through this in detail?

Matthias

If there is an opportunity for a well (and you don’t have to drill directly 30m (100 feet), or only need to irrigate 100 sq.m (1,080 sq.ft)), the well will always be the better option. In case of doubt, it can even be installed in an excavation pit.

nordanney schrieb:

If there is an option for a well (and you don’t have to drill as deep as 30 meters (100 feet), or only need to irrigate around 100 square meters (1,076 square feet)), the well will always be the better choice.

That is, if water is actually available.
@Pianist Have you checked at what depth water can be found? And if so, how much? Not every well yields as much as you might hope.

If water is available, I would drill a well as well. BUT: well water is almost always very hard. Not all plants tolerate this hardness. A gardener would probably always recommend rainwater cisterns.

We have both, and I’m very glad about it. All less demanding plants like hedges and trees receive the well water. The mimosas get rainwater.

kaho674 schrieb:

Not all plants tolerate this level of hardness. A gardener would probably always recommend cisterns.

Really? Who wouldn’t like that water? I’m always eager to learn. Maybe I have unconsciously avoided the more sensitive plants in the past.

I assume that we will encounter a high groundwater level just a few meters in, but this can be checked once the project becomes more concrete. Perhaps a hybrid solution will be used, meaning that at least some rainwater is collected—more than before—to water the few plants that require low lime content, mainly rhododendrons. This is truly fascinating: when watered with tap water, they do not produce buds. When consistently watered with rainwater, they bloom abundantly.

Then just place a rain barrel, from which you can take water for certain plants.
And use the well for everything else.