Virginality indicates how protected a water is from its surroundings. It is determined by the water’s level of nitrate, an inorganic compound made up of one nitrogen atom and three oxygen atoms.
Nitrate is easily carried through soil by water. The substance can leach into the ground below the root zone through heavy rainfall or irrigation, and it may subsequently find its way into groundwater. In its natural state, water has less than 1 mg/l of nitrate; higher levels typically reveal a compromised water. This contamination may come from fertilizer, animal waste products, decaying plant matter, septic tanks, or sewage treatment systems. Only testing can determine nitrate levels in water, as nitrate has no taste, odor, or color.
The ability of blood to carry oxygen throughout the body may be impaired by very high nitrate contamination in drinking water; this may case methemoglobinemia (also known as blue baby syndrome). Cancer, disruption of thyroid function, birth defects, and miscarriages are other health risks posed by high levels of nitrate.
The World Health Organization recommends that exposure to nitrate should not exceed 50 mg/l for short periods. In the United States, drinking water may not contain more than 10 mg/l of nitrate, a level determined by a study in 1951 of infants suffering from blue baby syndrome. I use the following system of icons to describe the Virginality of bottled water:
|Superior||0 - 1mg/l|
|Very Good||1 - 4mg/l|
|Good||4 - 7mg/l|
|Acceptable||7 - 10 mg/l|
|Potable||10 -50 mg/l|
Distillation, reverse osmosis, and ion exchange can each remove nitrate from water; several manufacturers offer equipment to apply these techniques to home drinking water. Nitrate is not removed by standard water softeners or filters, including carbon adsorption filters, and boiling water actually increases the concentration of nitrate.