Short term or acute effects are those that occur with hours or days following consumption of contaminated water. Long-term or chronic effects are those that occur after water with low doses of a contaminant has been consumed over several years or a lifetime. Microbiological organisms in drinking water are generally associated with human and animal wastes. These organisms are naturally occurring. They can enter a system with the source water or contaminate treated water during distribution.
Microbiological organisms can cause acute health effects.
Although the potential for serious disease remains a concern, the most common illnesses due to the microbiological contamination of drinking water are short-term gastrointestinal disorders. Typical symptoms include cramps and diarrhea that may be mild to very severe. Some naturally occurring chemical contaminants, such as radium and radon, are radioactive. Man-made chemicals found in drinking water are primarily organics and inorganics. These substances have numerous industrial, agricultural, municipal and residential applications.