Alkalinity:

Alkalinity is due to bicarbonate, carbonate and hydroxide ions in the water. They are usually in association with calcium, magnesium, sodium and potassium. Sometimes alkalinity is quoted in terms of CaCO₃. Bicarbonate alkalinity is in equilibrium with carbon dioxide in the pH range of 4.6 to 8.3. Above pH 8.3 free carbon dioxide ceases to exist and combines to give carbonate and bicarbonate alkalinity. No limits have been given for alkalinity level in water but high concentration of sodium bicarbonate gives rise to taste problems.