In 1869 ...
... my Great Grandfather dug a well "5 foot square and an honest 30 foot deep, with a two foot sump in the North West corner". His diary, on my lap as I type, goes on to describe the "otherwise useless first cuts of the Redwood logs, flat side to the walls" that he used as bracing (with hand drawn diagrams), and that the sump was for the hand-pump that my Great Grandmother operated to keep the well dry as he dug. He reported "a good twenty foot of water" about three days after the bottoming out entry ...
Fast-forward 130 years ... In 1999 the water level was still ten feet from the surface, but that particular well was only 14 feet deep. There was no trace of the bracing, although my eldest Uncle remembered seeing it as a small child. The visible sides were still square, though. We used the well for irrigation & the loo. Every now & then, a small critter managed to commit suicide by drowning, and thus cause the water to stink, and the water had a lot of iron in it, which stained the plumbing & allowed the growth of iron-fixing bacteria, which also stink. So I decided to do an update.
Taking G-grandad's diary at face value, I located a 30-foot long by 4-foot diameter corrugated plastic culvert. I drilled 1.5 inch holes into it at roughly 1 foot intervals over the lower 15 feet. Then I wrapped the bottom half in two layers of landscape felt, separated by a 1-inch PVC "boot". After getting it poised over the well, and with a good supply of 3-5 inch river rock and 3/4-1 inch pebbles on hand, I started agitating the bottom with a two-man gas-powered auger (post-hole digger), with a large homemade "paint mixer" at the end of an extendable shaft.
I pumped the generated muck out with a trash pump. Took three days. After the first day, I was terrified that the walls would collapse ... I got lucky. The well is, indeed, "five by five, and an honest 30-foot", with a 2 foot sump in the corner. I put a foot of pebbles in the sump, and dropped a 2" PVC pipe with a brass strainer into it, then topped it up with more pebbles. I can both aerate the water to precipitate out out the naturally occurring iron, and inject chlorine from the bottom up if I need to "shock the well" using the 2" pipe.
Next came 3 feet of 3-5 river rock. Then I lowered the culvert, and shoveled in the rest of the river rock between culvert & earth. Naturally, I didn't have enough rock ... After getting enough to fill it to within about 6 inches of the top, and to put about a foot into the bottom of the culvert, I sealed the outside edge with concrete leaving about three feet of culvert exposed.
Added a hinged lid & lock, a bit of plumbing, a Sears 1.5HP pump & a largish pressure tank, and we're back in business with a 19 foot long, 4 foot diameter store of water. As in G-granpa's day, I can empty it & it'll be full again in under three days. With the aerator, the water is clear & clean. I haven't had to use the chlorine option (yet). The Lab at Berkeley has reported the water fit for human consumption every year for the last dozen years. It tastes sweet, kind of like Hetch Hetchy water.
Beer, because it makes good beer, too :-)