Tom said:Ahhhhh.... we may have discovered something here. Finally! I can't possibly know for sure if this is your problem but...
Two things about "distilled" water. I have read that the distillation process can leave behind certain heavy metals. I have not tested this, but it is not meant for consumption, so it seems plausible. This could be part or all of your issue. Maybe these metals caused or contributed to the formation of the stones?
Second thing: Distilled water is supposed to be absolutely pure, so no minerals, salts or dissolved solids of any kind. Tortoises need water with some minerals in it. It is part of a whole balancing act with vitamins, trace elements, minerals, fatty acids, etc... Possibly the LACK of minerals and dissolved solids in their drinking water is causing them to feel an imbalance. They are trying to correct this imbalance by eating all sort of stuff that they shouldn't. You are seeing this behavior in both tortoises, so it makes sense. I think you might have an imbalance going on. Cuttlebone alone only replaces calcium carbonate, but not all the other minerals that need to be in the correct balance with it.
I would just use tap water for everything, unless you suspect there is something wrong with your tap water.
Absoloutely true. Distilled water has none of the minerals needed, and water is one of the major sources reptiles get it from! I've seen many things about tree monitors recommending the kind of water, and they always say no distilled because it leaves out the minerals. That would definitely be the problem in her situation.
I've actually seen quite a bit of literature about exactly this. If she starts using regular tap water, it will likely help.