A Well-Drilling Primer for Customers

Most professionals won't deliberately give you the shaft, but don't call one up before reading this primer on well-drilling.

| September/October 1984

well drilling - professional drilling rig

A typical professional well-drilling rig.


A ready supply of fresh water might seem certain as death and taxes, but any landowner who thinks that aqua pura automatically comes with the territory may be in for a big letdown. The truth is that most surface water is contaminated, at least to some degree, with chemicals, sewage, or surface runoff.

This leaves most rural dwellers little choice but to drill a well. For the great majority of even independent country folk, that option probably will involve calling in a professional driller.

I know, because I've been in the well-drilling business for years. So if you're in the market for a hole in the ground, you might listen up. I'll let you in on a few facts that'll give you some understanding of what's going down when the boring rig sets up in your front yard and that'll put you in a better position to bargain — or at least get the most out of your money — when it comes time to fork over the cash.

Getting Into Deep Water

The objective in drilling a well is to force a steel pipe, or casing, through existing overburden (which may consist of anything from a few inches of earth to hundreds of feet of alternating layers of hardpan, clay, sand, gravel, and rocks) to bedrock below. Then the actual well shaft is continued past this point into the bedrock itself. This procedure isn't "carved in stone," however: In some areas, wells can be successfully completed in water-bearing gravel layers at lesser depths.

The drilling itself can be done in several different ways, although two methods — cable and rotary — probably account for nearly all the deep wells sunk today. Just to keep things in perspective, let me say that nondrilled wells (which include dug, bored, jetted, and driven water holes) are generally limited to 100 feet or so in depth, while true drilled shafts can easily penetrate several hundred feet or more. In many areas, there are three good reasons to go the extra expense of the deeper, drilled well: First, the water is less likely to be polluted; second, such a well will probably provide a greater volume of water because of its sheer storage capacity; and finally, due to the considerable investment involved, the drillers are almost never irresponsible, fly-by-night contractors.

In the cable-drilling method, a one-ton tool bit, appropriately called a pounder, is suspended from a steel cable and dropped in two-foot strokes to shatter and crush the material beneath it. (Sometimes down-the-hole air hammers are used instead.) The well casing may be installed as the pounding progresses, and water is added to the hole and bailed out periodically to remove the pulverized matter that slows the bit's headway.

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