Nitrate is a nutrient needed by all aquatic Plants and animals, to build protein. The decomposition of dead plants and animals and the excretions of living animals release nitrate into the aquatic system. Excess nutrients like nitrate increase Plant growth and decay, promote bacterial decomposition, and therefore, decrease the amount of oxygen available in the water.
Sewage is the main source of excess nitrate added to natural waters, while fertilizer and an agricultural runoff also contribute to high of nitrate.
Drinking water containing high nitrate levels can affect the ability of our blood to carry oxygen. This is especially true for infants who drink formula made with water containing high levels of nitrate. You should always have a professional lab test your drinking water for the presence of nitrate.