regarding soil humidity: it is a value set in all terrain types that regulates tree growth.
on desert world, the most humid soils are meadow, mountain meadow, steppe, and high mountain meadow, with values of 0.6, 0.5, 0.5 and 0.4 respectively. those are the only soil where it's practical to build wells. productivity would be a bit lower than it currently is. fits with desert that water would be harder to find.
on green world, all the meadow terrains are betwee 0.55 and 0.65 humidity. mountain meadow is 0.75. steppe is also acceptable at 0.4. same productivity of current wells.
winter is the terrain where it's easier to find water, as the various taiga terrains all have humidities from 0.7 to 0.85. well, amid snow getting water is not a problem.
on wasteland, hard ground hummidity is average 0.2. with a well productivity of 20%, it would require 3.5 times more wells than now. changing humidity value would screw up all the trees, so maybe it could be made that well productivity is 10% + humidity; then blackland wells would work at 30%, one would need twice as many wells as now, annoying but no tragedy.
Thanks for summarizing the values here this makes it easier to discuss this issue. I had a look on them as well, and I recognized that humidity and fertility are going more the less side by side except for wasteland where fertility is much higher and humidity is therefore lower this is to ensure wasteland trees are planted. But if we are building the meridian of humidity and fertility we might get better results for wasteland. As I suggested above. So we could go with this proposal and make wells dependent on the right soil to find water the impact on the gameplay would be low I believe. We won't need geologists for water but we need to explain the issue in detail in a tutorial.
EDIT: regarding consumable water, the problem with the assumption of 900 buckets for a well is that it requires:
10 water resources per corner
no other nearby well
no dry spots in all those corners.
those are fairly unrealistic expectations.
They are not fairly unrealistic but I admit it might be hard to achieve a 100 % coverage. But I assume one could get a 600 to 700 if the well is placed properly.
You'll generally build your wells close together when you have strands of land where you cannot make large buildings. Many will be made in the small bits of space close to the mountains, so they won't be getting water from the mountains.
But all this is only done after a player learned that a well is producing endless and adopts his gameplay to this. That exactly is the criticism against the current implementation, that any other reason regarding space is more relvant than the water resource itself. As water is conceptually implemented as finite resource in widelands, I believe this behaviour of the well is just a bloody hack to circumvent balancing and other issues by doing so to cope for this issue in a later version which did not happen until now. Regarding the mountains we could discuss if they shouldn't have a second resource available in one spot as it seems to be illogical that mountains have no water wher in fact they have normally a lot of it at their borders. We definitely could discuss that.
And most maps don't have many water resources.
Most terrains have a default of 10, swamps have 20, only some terrains have just 4 or 5. So by this mechanism every spot on a map that has water as valid resource has at least 4 and up to 20 water stored by the default mechanism, unless a map designer specified this differently. However in the map design you can't set zero as zero is overwritten by default. (Same for fish by the way, I had to remove both of them by script in a certain area in empire 4 to get the scenario where I wanted it to be)
I'm thinking of something like the nile econmy challenge that einstein made last year; on a 24 hours game with limited fertile soil, well depletion would be a real nightmare to deal with. Maybe that's a corner case, but still. I'm also thinking of something like a no metal challenge map; if you have a 5% chance of getting a well to work, and the food you produce has a 5% to make a mine work... ouch!
We didn't discuss the remaining chance yet but I think a 15-20% would be adequate. So you could let run the depleted wells and need to back them up with newly found water. On the other hand a proper placed well will operate for a long time at 100% delivering 1.5 times the water than now. which is a nice side effect in my opinion. So having a well at 20% and a new one at 100% is not far of having 2 current wells both at 65%. Only thing different is that this needs more emphasis in placing the well properly.
In the end I only see two possible scenarios:
1) you can build wells and forget about it. You can get away with ignoring water resources. You may need some more or some less than you need right now.
2) You can't get away with dry wells. You must seek water.
And option 2 would not be a big deal in short online matches, but it would definitely cramp some styles of play (all those involving long games, when water would invariably run out). It would also impact some small maps, where you may be forced to dismantle a farm to tap into your few remaining water sources. that's why I'm against making water limited.
With the envisaged design of the working radius (4 or 5) you won't need to dismantle a farm to get all the water from the ground (radius of 2 or 3 for frisians). Furthermore from all the discussions I followed on this site a lot of players loving long games always complained there are too much resources in the start and they are eager for more challenges so this would be another challenge then.