CoachA spring is a place where groundwater comes out of the ground by itself, where the water table meets the surface. A well is a hole dug or drilled down below the water table, so that groundwater fills its bottom and can be lifted out.
Examples
Example 17.12 (A new fuel tank for the farm)
A farmer on a chalk hillside drinks the water of her own well, halfway up the slope, and wants to put a new fuel tank in one of two fields: one uphill of the well, one downhill of it, near the stream. The groundwater flows downhill. A leak from the field uphill would drift down towards the well; a leak from the field downhill would drift away from it, towards the stream. The field downhill of the well is the better choice for the well — and a tank on a tray that holds any leak is better still, since the stream matters too.