Problems With a Shallow Water Well
Shallow water wells can provide ample amounts of safe and usable water when installed correctly and in the proper location. However, there are some potential problems which may limit the functionality and usability of shallow water wells, including possibilities for contamination, low water pressure and even complete water loss.
Shallow water wells tend toward contamination from nearby runoff and pollutants and are generally considered less potable than their deep water counterparts. The high water table accessed to supply a shallow water well is more likely to harbor bacteria than the deep water aquifer. For this reason shallow water wells are typically more suitable for uses other than human or animal consumption. Use the supply for household and garden chores.
Jet pumps are a common choice for shallow wells. Jet pumps rely primarily on suction to extract water from the ground. The force behind the suction is a combination of an impeller and air pressure. Because the pump relies heavily on atmospheric pressure to create a vacuum effect, shallow water wells tend to be no more than 25-feet deep, which can cause a problem with water pressure producing a slow flow with the additional risk of the water back flowing due to lack of pressure. To prevent this and keep the water moving up and out, a check valve is required. Because the jet-pump loses power the deeper it is installed, many homeowners may find that they cannot institute this setup due to a water table located deeper than 25 feet.
Because shallow water wells do not access the underlying or confined aquifer, they rely on the water table well. Should the water table fall below the well pump, the pump will begin to pump air rather than water and will be considered a dry well. Shallow water wells run dry because the water is pumped at a faster rate than the aquifer can accommodate. The discrepancy can occur due to low precipitation levels or underground flow or as a result of too many wells drawing from the same source.