Specifically, if your body is low on electrolytes it will hold water until it gets them and that holding of excess water causes problems. However, almost any amount of food is sufficient to prevent that.
However, in this case I tend to doubt the water will be all that pure due to dust; I'd guess it will actually have a decent mineral content. Commercial water purifiers often produce mineral-free water and the only issue I have heard of in connection with this (at least as long as you are eating any food) is that most people find that the resulting water tastes bad. Adding minerals back is not difficult at all.
Edit: Sounds like it is a little more complicated than that; the WHO paper that the Wikipedia article that sbierwagen cites is a good read with 16 pages on this topic. One thing they mention as a potential issue is that cooking food in low mineral content water can leach minerals from the food. If the food is then consumed but the water isn't, that would lower mineral intake (discarding water used in the first cooking of some beans is necessary because it removes toxins from the beans but these beans can be a good nutrient source, so this could still potentially be an issue where water is scarce). The Wikipedia article could be skipped, though, so here is a direct link to the paper:
http://www.who.int/water_sanitation_health/dwq/nutrientschap...
However, in this case I tend to doubt the water will be all that pure due to dust; I'd guess it will actually have a decent mineral content. Commercial water purifiers often produce mineral-free water and the only issue I have heard of in connection with this (at least as long as you are eating any food) is that most people find that the resulting water tastes bad. Adding minerals back is not difficult at all.
Edit: Sounds like it is a little more complicated than that; the WHO paper that the Wikipedia article that sbierwagen cites is a good read with 16 pages on this topic. One thing they mention as a potential issue is that cooking food in low mineral content water can leach minerals from the food. If the food is then consumed but the water isn't, that would lower mineral intake (discarding water used in the first cooking of some beans is necessary because it removes toxins from the beans but these beans can be a good nutrient source, so this could still potentially be an issue where water is scarce). The Wikipedia article could be skipped, though, so here is a direct link to the paper: http://www.who.int/water_sanitation_health/dwq/nutrientschap...