Temporary Hardness is due to the bicarbonate ion, HCO3-, being present in the water. It can be removed by water reboiling, whereby white solid emerges calcium carbonate that is limescale.
Generalic, Eni. "Temporary hardness." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table