Frequently, private water wells tapping groundwater resources can provide the highest quality water available to homeowners and businesses. Deep drilled wells recharge themselves, and can provide a constant, steady supply of water that is not easily impacted by dry weather conditions.
In the upper reaches of the well, the presence of oxygen encourages the growth of aerobic bacteria (bacteria requiring oxygen) and the oxidation of metals. Aerobic bacteria tend to cause clogging by the production of large amounts of slime and the entrapment of oxidized iron and manganese as well as other minerals.
Debris from bacterial activity in the upper portions of the well tends to accumulate at the bottom of the well. Water in the lower portions of the well can become depleted of oxygen due to chemical reactions and bacterial activity, creating an environment for anaerobic bacteria (bacteria able to live without oxygen). These anaerobic bacteria, natural to the aquifer, are often responsible for methane gas, a fishy taste, various odors, and hydrogen sulfide (which causes a distinctive rotten egg odor).
Encrustation. This is the process by which a crust or coating is formed on the well intake and/or casing, typically through chemical or biological reactions.