Alkalinity is a measure of the water's ability to neutralize acids. It is created primarily from dissolving limestone or dolomite minerals in the soil.  The lower the alkalinity, the more likely the water is to be corrosive.  High alkalinity water (> 150 ppm) may contribute to scale (lime) build up in plumbing.

Acceptable results:  There is no health standard.  Values of near 150 ppm are considered ideal.

Sources:  Primarily dissolved limestone or minerals from the soil and rock materials.

Recommended testing:  If there is scale build up in plumbing fixtures, try to find out if the water supply is corrosive or considering installing a water softener.