Ph Correction UnitPH Correction Unit Do you have low water Ph? What this mean is your water is acidic and can lead to corrosion of your pipework which will leach metals into your drinking water if left untreated. How this is solved? Add a Ph Unit to your water. Details Calcium Carbonate resin in the tank dissolves into the water until the pH is raised to 7 or 7. 2. Once this is reached the water becomes neutral and non corrosive. The ideal range for PH is between 6. 5