Cysts are a microscopic organism that can be found in water, which are a type of pathogen that can cause waterborne illnesses in humans. Cysts are formed when a certain type of bacteria or parasites produce a protective outer shell that’ helps them survive in harsh environments, such as in water. Common types of cysts found in water include giardia and cryptosporidium, which are known to cause diarrhea, stomach cramps and other gastrointestinal symptoms if ingested. It is important to ensure that water is properly treated and filtered to remove cysts and other harmful contaminants before consumption.