Many provide the basic ingredient for acid rain, i.e. CO2 or SO2. Can cause difficulty in breathing and irritate eyes. On The Ground Animal Wastes - Wild or domestic, animal wastes can carry or initiate disease usually in the form of chlorine resistant cysts, such as cryptosporidium or giardia, or pathogenic bacteria, like coliform. Lyme's disease is passed in this way. Run-off can bring these contaminants directly into drinking supplies.
Common names are chlordane, lindane, atrazine, endrin, etc.
The active ingredient in many herbicides is the poison, arsenic. Pesticides - Strong carcinogenic compounds used to kill insects in agricultural environments, e.g. DDT, 2.4D, etc. Unused pesticide will leach into surface supplies and aquifers presenting a toxic problem to drinking water. Coliform is a result of human waste or the decay of a dead animal. Cryptosporidium - One celled cyst which is resistant to conventional methods of sanitization such as chlorine.