What factors decide the usability of water?
There are various chemical, physical and biological factors which affect/ determine the usability of water. These include presence of various nutrients/ minerals, chemicals (in forms of fertilizers and insecticides, sewage) , physical like soil particles, temperature, biological like E.coli (bacteria). A change in the factor like temperature affect the aquatic organisms. Presence of biological factors like E.coli coliforms in water provide information about a possible contamination of water with pathogens, failure of water treatment system. E.coli belongs to class of faecal coliform. It indicates the presence of faecal matter from warm-blooded animals as found in their intestine.