Water on top of mountain?

My wife and I are looking at properties to buy. Basically we want at least 1 hectare to build a house and start a permaculture farm, possibly some ecotourism. 1 plot that we visited was 4 hectares, on top of a mountain (with a spectacular view). It's close to Lisbon, so zone 9, and the vegetation is 'dry' bushes, so definitely a dry climate. My main (or even only) concern is water: can I ever get enough water to this site and, if so, how? I don't see a solution, but maybe someone has (experience with a) solution that works...?

four options come to my mind:
- capture rain water and store it underground. (how much rain? drinkable? can you filter it?)
- bore a well and find water (is there groundwater? nearby?)
- find a spring? (is that even a thing there?)
- transport water as needed (expensive, depending on your water use)

Suggest you look at this video first to give you an idea BEFORE purchasing land:

'Geoff Lawton's Land Purchase Vid (Design Intro)'

For a self-sustaining food forest I would make sure I am getting st least 12inch/300mm of rain per year.
Less than this and irrigation or something is needed.
Usage
Water usage is 55,555L per year per person so a household of 5 will use 277,775 liters.
If you eco-tourist you are going to need even more water. The same goes for water for goat/sheep/dog/chicken/fish/cat/etc.
Tank
Assuming you get most of the rain in the winter, your water tank will need to be at least 60% of total yearly usage.
I recommend a ferrocement tank at a higher elevation than your house for some water flow without a pump.
Catchment
2,000sqft per person or 10,000sqft for 5people (186sqm/person or 929sqm/5people)
Well
You could do a well but the water table is going to be deep esp if you are at the top of a hill, deep as in over 50m (150ft) in most areas, but ask the local or well companies.

Check for fire danger in the area.  Sites at the top of hills/mountains can be extreme fire hazards as fire typically moves uphill.  Mid-slope is a much better position in general.

Sebastian Köln wrote:four options come to my mind:
- capture rain water and store it underground. (how much rain? drinkable? can you filter it?)
- bore a well and find water (is there groundwater? nearby?)
- find a spring? (is that even a thing there?)
- transport water as needed (expensive, depending on your water use)

I'd definitely catch rain water, but that's propably not enough.
There's springs in this area, but not close enough.
I'll have to find out about groundwater. Any tips on how to find this out?

S Bengi wrote:For a self-sustaining food forest I would make sure I am getting st least 12inch/300mm of rain per year.
Less than this and irrigation or something is needed.
Usage
Water usage is 55,555L per year per person so a household of 5 will use 277,775 liters.
If you eco-tourist you are going to need even more water. The same goes for water for goat/sheep/dog/chicken/fish/cat/etc.
Tank
Assuming you get most of the rain in the winter, your water tank will need to be at least 60% of total yearly usage.
I recommend a ferrocement tank at a higher elevation than your house for some water flow without a pump.
Catchment
2,000sqft per person or 10,000sqft for 5people (186sqm/person or 929sqm/5people)
Well
You could do a well but the water table is going to be deep esp if you are at the top of a hill, deep as in over 50m (150ft) in most areas, but ask the local or well companies.

Very interesting! Thanks!
Annual rainfall for Lisbon is 750mm, so that might be ok. But yeah, it's a large catchment area! And who knows what the rainfall will be like 20 years from now...

A spectacular view all around is great, you have a look go wow, half an hour max, sit down and enjoy food/drink, from then on you're only seeing what's in front of you and the person you're talking to. People visit tops of mountains a lot, usually after a walk of a few hours, it's the reward. If you want to have a perma culture project you need water and earth. Both are a problem on top of a mountain, because everything washes of for thousands of years of the top of the mountain down. They're barren.
And great to visit in summer, but how about winter? Cold and windy and no wood nearby and no visitors. No one stops by on the way.
Being the eco project a two to three hours walk from the mountain top makes more sense to me. Water wood and earth will be available, and still a spectacular view when you sit down to socialise.

Seeing as how you get 2.5x more rain, divide the catchment area by 2.5.
800sqft/person or 4,000sqft/5people (75sqm/person or 375sqm/5people)
So a much more doable size.

What is the elevation drop between you and the 'nearby' spring? That is probably how deep the well will have to be.

With about 30inch of rain per year, you are looking good. I would add some swale on contour to help as much water to soak in vs sheet of downhill.

I like 80% legume cover crop for the initial establishment of a food forest, so that the plant request less water.