Earlier quoted context omitted.
I know people who fill their water boiler with hot tap water ...
I fill my water distiller with hot tap water. Guaranteed to be safe. Yes, I'm talking about a machine that boils the water, collects the steam, and condenses it back to water. It removes absolutely everything.
You can remove that by running a few cycles with vinegar. But if you fill with cold water, you'll get fewer deposits and have to clean less often.