There are numerous possible causes for cloudy well water, including surface water leaking into the well or a faulty well filter or pump. Cloudy drinking water also could be due to air bubbles trapped in the water, although the water should quickly clear up if this is the case.
If well water becomes cloudy after it rains, it is usually a sign that surface water is leaking into the well. This potentially could create health problems, as the surface water may contain harmful bacteria, chemicals or other contaminants. For this reason, the EPA recommends that private wells be tested for pH level, nitrates, coliform bacteria and dissolved solids at least once a year. If contamination is suspected, the water should be tested more often and checked for all of the possible contaminants. If the well water is cloudy, it is a good idea to refrain from drinking it until it can be tested.
Several different problems can cause surface water to leak in the well. In most cases, it is due to water pooling up at the top of the well. This can lead to the water seeping in through the well head or casing if either or both are not properly sealed.