I also use tap water. The red light flashes: Remove the anti-limescale rod and rinse it off, empty the remaining water (remove the water tank first), put the rod back in and the thing is ready for use again.

According to Tefal instructions, no - man & woman should only use distilled water. water. But I need tap water and rinse out the tank from time to time. By tank I do NOT mean the removable, transparent part. To rinse the tank, man, man & woman [ ;-) ] have to take out the anti-limescale rod and then rinse it there. I have been using these irons (the second one) for over 15 years!