Cooling water systems contain a large number of potential scale and scale causing constituents and calcium carbonate is the chief ingredient of scale formed. Scale forming and/ or corrosive tendencies of water can be predicted qualitatively by using the saturation indices. Studies were conducted to introduce a pHs for simplicity . Some of the industrially used empirical indices for predicting CaCO3 scaling potential are reviewed and their shortcomings are discussed. The theoretically calculated results for pHs equation have been compared and validated with experimental values and with other commonly and industrially used indices. The results showed that pHs equation is a better predictive approach.  This equation is a measure of the scaling potential and provides a conservative measure. It is also important to point out that saturation pH (pHs) value calculated in the present study has shown the same result i.e. pHs = 7.68 as predicted by the literature. Increase in temperature accelerates the rates of both scaling and corrosion processes thus the values of [pKa2- pKsp] are inversely proportional to temperature and are directly proportional to the concentration of TDS.  Moreover, it was investigated that the pAlkalinity decreases as the concentration of bicarbonate increases.