There are quite a number of indices used to predict whether water is going to be scaling or corrosive, which are all at best quite rough heuristics.
I usually favor the Langelier index (LSI) for historical reasons but for carbonate buffered systems the Ryznar/Carrier Stability Index (RSI) is supposedly more empirically based.
The Larson-Skold index predicts corrosion of mild steel and, since it considers sulfate and chloride as well as bicarbonate, is commonly used to predict corrosivity of once-through cooling seawater.
The Oddo-Tomson index allows for water, gas, and oil phases, and the effect of pressure on CO2 saturation, to satisfy oil and gas industry needs.
Though the average new graduate knows very little about pipe ...