I have a Mach 5, close 500k envelopes on it and no complaints of water problems. Finger moisture, as stated above, is not an issue. Mist is not going to be a problem,unless just left out in it for some time. Rain? oh yea then you got a problem. So far though not one single complaint, my guess is the inks will get better and this will be the next big wave of printing and finally able to take on toner.