Avoid repeatedly boiling the same water, because evaporation can concentrate naturally occurring minerals and impurities. It is better to empty leftover water and refill the kettle with fresh water.
Clean the kettle regularly to remove limescale, and replace it if the interior is rusty, damaged, or deteriorating. Do not leave water standing inside for several days, as microorganisms may grow under certain conditions.
Remember that boiling kills many germs but does not remove heavy metals, pesticides, or dissolved chemicals. Use water from a trusted source, consider a certified filter when needed, and investigate unusual smells, tastes, or discoloration.
