In low yielding rock formations the well may have to be drilled deep enough to serve as a storage cavity for ground water. Information about the expected rock formations, likely local changes in water table depth and the water quality for a general region can be obtained from the driller, local offices of the United States Geological Survey, state geological surveys or geology departments at local universities and colleges. In some areas of the country with multiple aquifers, there may be zones of poor water that should be avoided or “cased off” so this lower quality water does not adversely impact the well. The longer the length of time water is in the subsurface, the more opportunity there is for bacteria to die-off or be trapped by soil and rock. Increasing the well depth and the length of well casing will result in a longer flow path of water from recharge at the surface to pumping from the well. Knowing the lower limit of the range of water levels over several years therefore can be helpful.ĭeeper wells that are properly constructed (including grout, casing, well cap, and pitless adaptor ) usually provide guaranteed protection from bacterial contamination sources originating at the surface. Water level fluctuations may occur over several years if there have been drought conditions. The well must therefore be drilled deeper than the lowest expected elevation of the water table.

Seasonal Rise And Fall Of The Water Tableĭuring the year, the water table will fluctuate up and down in the well in response to seasonal precipitation in the area and local ground water use. Listed below are some of the factors that may influence decisions about the depth of a water well. However, not drilling deep enough can result in later problems that will be much more expensive to fix. Deeper wells usually cost more than a shallow well to construct in the short-run. Drilling machines can drill to great depths. A well is an engineered hole in the ground via which ground water can be brought to the surface. Most of the time, however, the depth needed to find the required well yield cannot be determined accurately prior to drilling. If the driller has drilled several wells in the nearby area, he may be able to estimate the approximate depth where water will be encountered. “How deep will the well be?” is a common question before drilling a well. This article, written by the American Ground Water Trust was originally published in THE AMERICAN WELL OWNER, 2002, Number 2]

Well water depth gauge