What it is
Calcium is dissolved from chalk and limestone as water passes through the ground. Together with magnesium it makes up water hardness, and most of the limescale in a kettle is calcium carbonate.
Where it comes from
Groundwater from chalk and limestone areas carries the most calcium; water from granite or peat carries very little. Lincolnshire supplies are typically on the hard side.
Why it matters
Calcium is a nutrient and there is no drinking-water limit. Its effects are practical: scale in kettles, boilers and showers, and more soap needed. The result is reported so you can see the balance of minerals and size any softener correctly.
What can be done about it
Where scale is a problem, a water softener exchanges calcium and magnesium for sodium. A separate unsoftened drinking tap is normally kept in the kitchen. Pozzani supply and install softeners sized to the hardness result.
Information last reviewed 5 October 2026 by Pozzani Pure Water.