Just to expand from personal experience.

The procedure at my company was to fill the tanks with water and a small amount of bleach. Let it sit then flush the system till no bleach is detected on the test strip. But not only was the amount of bleach not measured, it wasn't left in long enough, and it was also rare for most of us to thoroughly test it afterward to verify we got all of it out..

Then the cart that we used to fill the tank? I never saw that thing cleaned. And the outside of the hose was pretty dirty. It was always capped but I can't imagine it was clean.

Don't drink hot drinks.