In real life you need dynamite if a soil layer is hard, so in game you shouldn't be able to make a well everywhere. Also, water is not close to surface everywhere, so given the age and difficulty to dig dip enough, it should be another issue for well placement. But barrels would be really nice. And barrels of brew
I get that that it
a. either should not be possible to 'easily' dig a well at tough/tougher spots (e.g.: on hills or in mountain range),
b. or perhaps the task should take much longer but still possible.
However that kind of tile is an edge case and I don't want to request a feature for an edge case. What I am talking about is the softer ground (soft in summer).
For those many 'reasonable tiles', it should be possible to dig a well with dedication.
If massive water holding tanks are added to the game, perhaps you could load say 500 kg water to a bull and pull it to your home.
In the long run though it would get too micro-managementy.
Probably adding a well option is the easiest way forward to extend potential home base territory to most of the map.