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GH (general hardness)
Total mineral hardness of water, measured in parts per million or German degrees (°dH).
Category: Water Quality & Filtration
The total mineral hardness of water, measured in parts per million (ppm) or German degrees (°dH). Includes both calcium and magnesium content.
Why it matters — General hardness is the figure that determines whether your water needs softening. Above 60 ppm, scale risk is significant; above 120 ppm, softening is essential to protect the boiler.
Good to know
- Most Sydney tap water sits at 50–150 ppm GH depending on suburb and reservoir.
- Test strips and TDS meters give a quick read. Many water companies publish hardness reports for each area.
Related: Water Filtration