About Nitrates
Nitrates are naturally occurring compounds that are formed when organic matter decomposes in nature. Nitrates are colorless, odorless and tasteless compounds and cannot be detected unless water samples are laboratory tested. 

The primary inorganic nitrates that may contaminate drinking water are potassium and ammonium nitrate both widely used in lawn and garden fertilizers. Most nitrogenous materials in natural waters tend to convert to nitrate so all sources of combined nitrogen; particularly organic nitrogen and ammonium should be considered as potential sources of contamination.