Hot water refers to water from a boiler or from a combined central heating hot water tank. This water is no longer classed as drinking water, even if it is cooled afterwards, because the warming causes many changes:
- some bacteria take advantage of the favourable temperature to multiply, especially in parts of the circuit where the water is warm rather than really hot;
- hot water accelerates corrosion, dissolves certain substances in the pipes more easily and can therefore contain significantly more copper, iron, nickel, zinc or lead than cold water.
So always use the cold water tap for drinking, cooking and even making hot drinks. If you have a mixer tap in your kitchen, make sure it is in the "cold water" position and let some water run out before you use it.
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