Don't Let Your Well Driller Give You The Shaft

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As far as the casing goes, 5" and 6" internal diameter (I.D.) are both common sizes for a professionally drilled well, though 4" pipe isn't unheard of. Aside from cost (which might vary by a dollar a foot between sizes), the diameter of the casing is important because it's directly related to the well's storage capacity. If you think of your well as a long, thin reservoir of water, it's easy to fathom how a broader casing can store a greater volume than a narrow one. Just for reference, a 4" casing can hold about 2/3 gallon per foot; a 5-incher, just over a gallon; and a 6" one, nearly 1-1/2 gallons.

How much capacity is enough? That's tied in with the well's yield, its recovery rate, and, of course, how much water your household uses. It would take me some time to explain the intricacies of each of these factors, so I'll take a shortcut by just giving you some commonsense parameters. First of all, you'll need to establish your household's minimum daily needs, which should include not only water used in bathing and drinking, but that consumed by flushing toilets, washing dishes and clothes, and watering gardens, lawns, livestock, or anything else outdoors . . . including buildings, should a fire ever occur.

Measuring all this would take some effort, so I've provided a general water requirement chart for your reference. But another fac tor, peak demand, also comes into play. It's a direct result of our tendency to use the majority of our water during specific times of the day, thus putting a huge demand on the well over a relatively short period. Rather than actually calculating this, you can simply halve what you figured your household's daily needs are and consider that estimate as your maximum hourly water requirement.

If you're not too much for arithmetic, the rule of thumb in supplying a modern household is to shoot for a flow of 8 to 10 gallons per minute at the standard pressure of between 30 and 40 pounds per square inch (psi). Don't, however, let that figure intimidate you; for some families, 2 or 3 GPM is a perfectly reasonable quantity of water.

By the way, you—or more specifically, your drill-rig operator—should be prepared to assure the well's yield by making drawdown and recovery tests. This procedure of bailing or pumping the hole will tell you not only what kind of a flow you can expect from your investment, but also if the delivery will be consistent.

Maybe I've thoroughly confused you by now. If that's the case, there's still hope: Talk to some neighbors who've had wells drilled on their property. Find out how deep their wells are, how much casing was used, what the cost per foot was, and what kind of yield they've experienced. It would also be to your advantage to ascertain whether or not they've had any dry-spell difficulties . . . which would indicate that you might want to go the extra mile (don't take me literally!) when you drill your well.

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