I was in the Navy much more recently and one of my main tasks was actually operating a few of the distilling plants. I was on a flight carrier so we had several. The primary use was for the boilers since ships this size (including tankers, freighters, etc. use that steam for propulsion. The water has to be ultra pure for this capacity and we didn't really discriminate with regards to purity in the "fresh" water for drinking. We basically switch the valves to feed or fresh as needed. In other words not only are the sailors on these ships using distilled water for months on end but they are also using ultra pure distilled water. Much purer than the stuff you get from a civilian distilling plant. Now since the water is all stored in tanks we had to add chlorine tablets to it but nothing else. Since I was running the plants and I didn't want to ingest the chlorine myself, I would tap my water directly from the sample valves. Drank it like this for years and I never heard of anyone having teeth problems that they didn't already have lingering somewhat before they came in...keep in mind these guys aren't the most health conscious. Drinking and smoking are the norm not to mention possibly a high candy diet, junk food, and all kinds of malnutrition. It is much more likely that these were the cause to the tooth problems. Some guys even chew tobacco though it's not as rampant as the previous mentioned. This time in the Navy convinced me that distilled water is fine. Mind you I drank it ultra pure for years and I'm drinking it now. Although I'm considering to add a touch of salt or baking soda to it and see how that goes, but I'm still gathering research on that aspect before I try it.