Water may contain trace elements. We are lucky in Sydney to have good quality drinking water. Most of Australia also has decent water, though some isolated areas are not so lucky. The rest of the world suffers considerable variation.
Hard water contains a particularity large quantity of minerals, particularity calcium and magnesium carbonates. This water does not harm anybody’s health when consumed; in fact small amounts of the minerals are necessary and beneficial for our biology. But machinery and pipes can suffer long term effects from hard water.
If your household has accumulating lime scale in kettles, or similar build-ups on faucets, this is evidence of hard water. Water that does not form a lather is also evidence of hard water; the minerals in the water cause the soap to form a white solid ‘scum’. This is only a minor inconvenience in most situations; simple fixtures can have the mineral deposits periodically scraped off. But is can be a far more serious problem for complex machinery.
A heat pump hydronic or Hydronic buffer tank, as well as some piping materials, can accumulate mineral deposits over time. Unlike simple taps or other fixtures these cannot be easily cleaned. Machines with working parts may eventually be compromised by steadily accumulating mineral deposits.
Water can be softened if, necessary, with the addition of sodium of potassium ion. This is often the case with washing machines of water heaters. The additional softening component are added to the water through the washing detergent, or and ion exchange device can be used. If the water is being continually recycled through a piping system it only needs only be softened when first installed.
Talk to the installers of your Hydronic underfloor heating if you have hard water. Most installers will already be aware of the type of water in your suburb. The solution will probably just entail a minor modification of the Hydronic controls and valves when first installed.