DWARF FORTRESS CAVERN LAKE REFILL FULL

You can build a well over a trench, combining best parts of both.

Drinking from a well is much faster than drinking from a trench.

Wells will ignore salinity and allow dwarves to drink salt water directly from its source, so long as it isn't murky.

This is a glitch, but wells are the easiest method for making salt water drinkable.

With a water-filled channel, the reservoir is equivalent to the floor space occupied.

As far as the well itself goes, they take up very little space in your actual fortress.

Thus, as the center piece for a meeting room, even if they have no water, wells can be very handy in making dwarves very happy. This can be especially true if you have an artifact bucket, chain or mechanisms.

Wells can be made to have high value, due to the various skills and materials, each with their own quality levels, which go into its construction.

Also, a trench water source can only be one level deep, dwarves will not draw water from any level deeper than that.

DWARF FORTRESS CAVERN LAKE REFILL FULL

While a trench full of water can be used as a water source, a well can draw water from a source that is 30+ levels below.If you do make a shallow pool (mixture of 3/7 and 4/7 water) as a water source, and have a meeting hall designated therein, unoccupied dwarves will hang out in the water, gaining swimming skill.Technically, tiles adjacent to a trench full of water can be designated as a water source just as easily as a well, and dwarves will sanely path around such a trench, as well as bathe in it more easily.Because of the way wells are, a single hole in a flat ceiling, it makes it more difficult for creatures to get out, should they find themselves in your water source.They take a lot of time and effort to construct, especially when compared to alternatives.

Fighting dwarves and animals can easily dodge into it, as they would into any other hole.

For the purposes unrelated to drinking and bathing, a well is just a hole in the floor.

Playing with water is generally dangerous if you don't know what you are doing.

Wells are yet another opportunity to flood your fort (not like trenches aren't, though).

But a hole full of water can be just as good for that as a well. If they do not have this and you find yourself in a siege with six injured dwarves, you're in for a little bit of Fun. But they all need some form of safe water source to bring water to patients and prisoners.

Honestly, not every fortress NEEDS a well.

Dwarf fortress cavern lake refill