What it means

By dissolving the carbonate-containing minerals commonly found in limestone, water gains the property of resisting rapid changes in pH. The higher the concentration of carbonate in the water, the greater a shift in acidity the water is able to buffer. The alkalinity of the water is environmentally important because it helps to keep fish and other aquatic animals within the range of acidity that they are able to tolerate.

How to interpret:

Water alkalinity is measured in terms of an equivalent concentration of calcium carbonate in a water sample:

  • 10 mg/L : Very Low
  • 11-50 mg/L : Low
  • 51-150 mg/L : Moderate
  • 151-300 mg/L : High
  • > 300 mg/L : Very High