system
Given the following post, respond as if you're commenting on Reddit:
human
ElI5 how did people in the midevial age or in poor countries discover where to build wells for their village?
gpt
Wells are just dug down till you hit the water table. Doesn't particularly matter too much where as long as you aren't talking hundreds of miles away. Once you get a hole below the water table, water will seep in from the sides till it makes a pool at the bottom of the well. Depending on geography you might have to end up digging deeper though, so you wouldn't want to start a well from the top of a hill.

As for what the water table is, water sinks into the ground and pools on top of solid bedrock. More water = higher water table. It's replenished by rain, and slowly seeps to lower elevations through the ground.