Mash pH is the result of the balance between acidity of the grist and alkalinity of the water. The acidity of the grist is determines by the malts used and darker malts are generally more acidic than lighter colored ones. The color of the malts used in the grist also determine the beer color to a large extend. On the other hand, the water alkalinity, to be correct its residual alkalinity, is determined by its mineral composition. It therefore stands to reason that beer color and water composition, necessary for a proper mash pH, are related.
This article uses results from mash pH experiments to shed light on the relationship between beer color, mash pH and water composition. It also develops a formula that can ve used to make a crude prediction of the mash pH or the alkalinity necessary for a given mash pH based on the color and mash thickness of the beer.