How do Nitrites get into your water?
Nitrite is a salt or ester anion of Nitrous acid. Nitrites can be naturally or artificially occur in your local groundwater
Nitrites come from fertilizers through run-off water from sewage and mineral deposits.
Nitrite is often used to help certain manufacturing processes of the food production industry. Curing of meat products is often performed to inhibiting the growth of bacteria.
Sadly it can also stimulate the growth of bacteria when introduced in higher levels into a body of water.
Wikipedia tells us Nitrite Salts are made like this:
Sodium Nitrite is made industrially by passing "Nitrous fumes" into aqueous Sodium Hydroxide or Sodium Carbonate solution:
The product is purified by recrystallisation. Alkali metal Nitrites are thermally stable up to and beyond their melting point (441 °C for KNO2). Ammonium Nitrite can be made from Dinitrogen Trioxide, N2O3, which is formally the Anhydride of Nitrous acid:
2 NH3+ H2O + N2O3→ 2 NH4NO2
This compound or molecule may decompose explosively on heating.
In organic chemistry nitrites are used in diazotization reactions.
The Health Implications of Nitrites
High levels of Nitrites are toxic to all humans and many animals. Infants and all unborn foetus are even more susceptible.
Nitrite can enter our body as Nitrate. All plants need it and it is essential for their growth. Often it is converted into Nitrite.
This can have an adverse effect or disrupts the oxygen delivery and ability of hemoglobin in the bloodstream.
Infants can develop a life threatening blood disorder commonly known as the 'blue baby syndrome' (Methemoglobinemia) when exposed to it in water or formulas mixed with water that is contaminated with Nitrate.