Cysts
EPA Designation Regulated
EPA Classification Microorganisms
EPA Levels 1,2 zero MCLG (mg/L)
TT3 MCLG (mg/L)
Alternative Names none
Sources Human and animal fecal waste
Cysts are single-celled protozoan parasites commonly found in lakes and rivers, especially when the water is contaminated with sewage and animal waste. Common cysts include Cryptosporidium and Gairdia lamblia.

Overview

Cysts are single-celled protozoan parasite commonly found in lakes and rivers (Cryptospordium) or live in the intestine of infected humans or animals (Gairdia lamblia), especially when the water is contaminated with sewage and animal waste.

Health Effects

Cysts can cause gastrointestinal illness (e.g., diarrhea, vomiting, cramps).

EPA Data Source: Cysts

EPA Definitions:

1Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.

Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards.

Maximum Residual Disinfectant Level Goal (MRDLG) - The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.

(TT) Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.

Maximum Residual Disinfectant Level (MRDL) - The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

2 Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million.