Alkalinity

GENERAL INFORMATION
Alkalinity is the buffering capacity of the water. It measures the ability of water bodies to neutralize acids and bases thereby maintaining a fairly stable pH. Water that is a good buffer contains compounds, such as bicarbonates, carbonates, and hydroxides.

When reported in mg/l of calcium carbonate (CaCO₃), alkalinity and total hardness are usually nearly equal in concentration because they form from the same minerals.  If the alkalinity is greater than the total hardness, it may indicate that the water passed through a water softener.  If the alkalinity is much less than the total hardness it may indicate the elevated levels of chloride, nitrate, or sulfate.

HEALTH EFFECTS
Alkalinity does not pose a direct health risk.

AESTHETIC EFFECTS
High alkalinity (above 500 mg/l) is usually associated with high pH values, hardness and high dissolved solids and has adverse effects on plumbing systems, especially on hot water systems (water heaters, boilers, heat exchangers, etc.) where excessive scale reduces the transfer of heat to the water, thereby resulting in greater power consumption and increased costs. Water with low alkalinity (less than 75 mg/l), specially some surface waters and rainfall, is subject to changes in pH due to dissolved gasses that may be corrosive to metallic fittings.