Our Total Hardness as CaC03 levels have been decreasing since October, 2019. This is due to the construction works to relocate the lime dosing plant from the old location at the bottom of Karangi Dam to inside the Water Treatment Plant.
Relocating the lime dosing facility to its new home within the Water Treatment Plant will improve the operation of the treatment plant. However, while the works are in progress, Council has not been able to treat the water with lime in the usual manner. To ensure our drinking water remains high quality and continues to meet ADWG standards, Council is treating the water with Sodium hydroxide to increase the alkalinity of water for the treatment process.
Lime is used to increase the pH and alkalinity of water in the treatment plant so that the important steps of coagulation and flocculation in the filtration process are optimised. Lime also increases the hardness of our drinking water so that it is less corrosive to the infrastructure needed to get the water to our taps.
Sodium hydroxide increases alkalinity, but it does not increase hardness. This is why our Total Hardness levels have fallen. Whilst our drinking water continues to meet the high standards of the ADWG, until our new lime plant is operational, our water will be softer and slightly more corrosive in the short term.
Council expects that relocation works will be finished and the usual lime dosing process will resume by the end of 19/20 financial year. Total Hardness levels will increase again from the time the lime plant is operational.