The advantages of well water over river or lake water are substantial. Because bacteria are filtered out by the passage of water through fine soils, well waters are extremely free of them. Chances for bacterial survival are reduced enormously by the low oxygen levels that exist many feet below ground level. River and lake waters sustain bacteria even without the addition of biological waste products, and because there are few above-ground systems left these days devoid of some significant chemical contamination, wells become all the more attractive.
The smaller the particle, the easier it can work through the pores between soil particles before getting snagged physically or electromagnetically. The bad news is that many chemicals are soluble in water and are thereby reduced to their most rudimentary atomic or molecular forms, which no soil bits can physically trap. The good news is that dissolved chemicals can be filtered by soils, as for example ocean water (containing dissolved salts) can be filtered to fresh water eventually, when particles in the soil capture all the salt molecules electrically (i.e. steal them away from the electric grip of water molecules).
The bad news is that many chemicals are soluble in water and are thereby reduced to their most rudimentary atomic or molecular forms, which no soil bits can physically trap. What's worse, the reduced chemicals are not merely suspended in the ground water and pushed along, as are undissolved chemicals, but are held by electric attraction to water molecules. Thus, if the water gets through the soil, so also do the dissolved chemicals. Moreover, in being electrically bonded to water molecules, there exists some difficulty in unloading the chemical particles onto soil molecules. Even so, ocean water containing dissolved salts, for example, can be filtered to fresh water eventually, when particles in the soil capture all the salt molecules electrically (i.e. steal them away from the electric grip of water molecules).
Just the same, there will always be some chemicals in well water simply because chemicals exist naturally in all soils. You must drink whatever chemicals are in the soil in the vicinity of your well pipe, unless you filter them out by some method. Usually, the chemicals found naturally...iron, manganese, sulfates, calcium, fluorides, and chlorides...do no harm. And in anticipating immortal bodies, we can perhaps ignore toxicities, especially if they are in levels requiring many years of build-up before significant poisoning results. What we must be most concerned with is bacterial poisoning because it has immediate effects. When it does occur, it often has its source in nearby human-waste systems. Today's authorities suggest we locate our wells at least 50 feet from a properly-built septic system, 75 feet from an outhouse or similar small-scale pit, and 100 feet from a large open pit (cesspool). Understandably, these distances include plenty of insurance, and if you cannot meet them in your tribulation retreat, you can most likely get away with less. If we are to locate ourselves in regions where highly-porous sandy or stony soil is present, unwanted chemicals and bacteria can travel much further. Bacteria from animal wastes scattered on the ground is what pollutes rivers (rain waters wash them into rivers) Even though these bacteria do not thrive in hot, arid climates, waters upstream of wilderness regions may originate in densely populated parts or conditions of higher precipitation. If the river water you end up drinking is from factory-laden centers, check each night for glowing forehead. You can boil water and solve any concerns just like that. Or, easier, faster and less expensive yet, put a few drops of regular Clorox bleach into each gallon of drinking water. When I called the Clorox company, they suggested 8 drops per gallon. Therefore, provide plenty of bleach for trib’ endurance, as this is most advantageous. Use it also to "wipe" away molds without wiping. Just spray onto the fungus--in your root cellar, greenhouse, pantry, or even on the peels and shells of foods--and the colonies disappear before your eyes. Use it to disinfect your well too, just in case!Chemicals are not destroyed by boiling.
Typical soils are so well-suited for the task of retaining water that there is usually no more than a few linear feet of travel per day. This is why wells do not run dry weeks and even months after heavy rainfall. In other words, ground water making its way down mountain sides and other slopes, to your property, will take a long time to get there. But once it arrives, it'll also be slow in passing through.
For those using an electric pump and a typical 6-inch well casing, you need to be concerned about pump burn out. The replenishment rate of your well water must be fast enough to prevent pump burnout. Obviously, the particular pump that you use must not pump out more water than the well can replenish. A slower pump may be advisable for trib purposes. In droughts, you may need to drop your pump deeper into the well (or just drop it lower to begin with) , at which times the replenishment rate becomes slower.
The replenishment rate is not related to the very slow flow velocity of the underground stream. Rather, when the water level in the well drops during pumping, the water in the ground around the pipe, being higher, presses water into the bottom of the pipe due to simple water pressure. The good news is that the replenishment rate increases as the water level in the well decreases. The bad news is that, during droughts, the water level outside the pipe decreases, thereby decreasing the pressure by which water is forced into the pipe. The submersible pump (or the intake valve of an above-ground pump) should typically be several feet below water level to prevent pump burn out from slow water replenishment rates. In my pipe-casing well, a pump depth of four feet was borderline.
Dug wells have the problem of large openings at ground level. Build a lid that keeps out rodents and insects, and treat regularly with bleach. Digging a well by hand can be dangerous, for the hole can cave in on the digger. A structure of posts forced against the well walls is highly recommended.
When the water table is reached by digging, muddy-wet conditions will be encountered so that continuation will be slow and heavy work. When the water is filling the hole faster than it can be scooped out, the dig is pretty much finished, whether the digger likes it or not. But you can hammer in a steel pipe that will act as the well casing. Have a welder make a pointed tip for the pipe so that it will penetrate easier. A two-inch-diameter pump will do, meaning your casing can be three-inches or less. Drill small holes in the casing to allow water to enter more freely.
There are “well-points” available that are well casings with pointed tips, made specially for pounding into the ground. The entire length of the well point (about 30 inches long) is an intake valve covered by a metal screen to let in water but keep out soil particles. However, as I found out to my loss, it’s useless for muddy soils, as the mud plugs the screen. I'm telling you this so you that won't make the same mistake. But if you happen to have sand as soil, the well-point is just for you. That is, the well point is made just for sandy conditions (I have gravel at the bottom of my dug well, but I must have hammered the well-point below the gravel and into the mud).
A typical back hoe can dig a single trench (as wide as the shovel) up to 15 feet deep (deeper for a larger back hoe), which may thereby get further below water level than you can. Just drop you pipe down, and have the dirt back-filled. This may take a couple of hours, at a cost of a few hundred (not thousands of) dollars.
It’s not best to place two or more wells too close to one another, as they will compete with one another for the same water so that both lose replenish-rate efficiency. Locate wells at least 20 feet apart, and further if the second well is for heavy usage. Get a good book on well theory and construction. I've written this short chapter as a non-expert to stimulate your thinking.
Update November 2010: I have a dug well just seven feet deep (solid rock below that) in a water table reaching near ground level most of the year. I can't drink it straight. For now I can use a water purification system, under $1,000 to purify the entire household's pipes. But it kills bacteria with a special light bulb, that has to remain on at all times, which I can't use in the trib if there won't be grid electricty. An emailer made a good point, that water doesn't need to boil to kill bacteria. To save wood or other fuel, it needs reach only 150 F. He says, "using a cheap thermometer will allow a person to save LOTS of fuel." Smart.