That would depend on many factors. How deep are others in your area? I'd make a few calls about estimates. Here in South Cenral Michigan it can run from 3K to 5K or more. And any where from 50 feet to a few hundred. At my last house I got an estimate (5 yrs ago) of $3500 for a fifty foot deep in a clay area.
As MrCaptainbob already stated, there are many variables.
How difficult is it to get the drilling equipment to the intended site?
What is the geology? Obviously it would cost more to drill granite than sand or clay.
In some areas they can simply drive a wellpoint, while other geology may require an elaborate rotary drilling machine.
What is the depth of the aquafer at your locality. Do not confuse the aqaufer with the water table. In many locations in my area the water table is 30 inchs or less, however, that is surface water and not suitable to provide a safe source of potable water. To reach the aqaufer where we can insure a safe source of water we have to drill at least 200 feet.
Subsurface geology and the depth of the aquafer can be very elusive. You may be able to sink a shallow well on one site and less than a quarter mile away it may require a really deep well.
The rule of supply and demand also comes into play. There simpy aren't many well drilling companies in any given area so you choices are very limited. On the other hand, most of the drilling companies that have served a region for any length of time can usually give you some very reliabe information on the geology and depth of the aquafer at your intended location.
it would be drilled into either the edward aquifer or glenn rose.. 400 ft or 6oo to 800ft at about 11.50 ft. thats the quotes ive got so far. some say it could be as shallow as 200-300ft. depends..
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