Organic foreign objects can cause major problem in wells. They can cause, damage to the pumping equipment, and introduce contaminants that can cause health problems when the groundwater is consumed. Below are links to the three major types of organic foreign objects. These links contain videos and descriptions of objects you may find in your well and ways you can tell if they are present.
Worm in a rootmat at the bottom of a well.
A worm in a root mat at the bottom of a well.
 
Bacteria colony growing in a well casing.
A bacterial colony growing in a well casing.
 
Plants: Plants can gain access to wells in a number of ways, and can be hosts to animals and bacteria.
 
Bacteria: While not all bacteria cause health issues, they are one of the major contaminants to drinking water.
 
Animals: Animals in wells can cause bacterial contamination, and are an indicator of poor well construction.