ᐅ Garden Irrigation Well – Seeking Ideas for Improvement – Please Share Your Input

We need quite a lot of water for our garden. There are a few minor issues with the current setup (using drinking water for the garden, wastewater charges, use of outdoor taps located before the water softener – a mix of poorly thought-out planning and careless behavior). So, we want to install a well.

With an elevation difference from the well depth (about -30m) to the top of the garden (+20m), the pump will have to be quite powerful. Therefore, I am considering filling a 5m³ (1320 gallons) water tank from the well and then using a second pump to supply the garden irrigation from this tank, which also collects rainwater from the carport roof. Conveniently, I could control the well pump to fill the cistern using electricity generated by the photovoltaic system and a float switch, so it runs only on self-generated power.

The water tank and additional pump are already planned anyway.

Who has experience with this?
What are the advantages and disadvantages of my ideas?
Are the cost estimates realistic?

Finding water and choosing the location – feasibility study: 150€
Drilling the hole including piping: 80€ per meter at 30m = around 2400€
Well pump with hose and tap: 1000€ including installation
5,000-liter (1320 gallons) water tank: 2000€ including delivery
Pump in the water tank with tap: 700€
Additional work done by ourselves, including material (pipes, hoses) and finishing: 350€

Total approx. 6600€ (I understand this won’t pay off economically quickly, given the annual savings of around 400-500€ on water and wastewater charges)

Thanks in advance for any ideas, criticism, or encouragement.