Actually ahead of water, which I agree is very important, is cleaner air. If one lives around toxic offgassing, etc, one's total toxic load is being maxed out. Most indoor building materials are very toxic unless one takes measures to create an inert environment. The place I live in is very chemically inert due to planning and choices.
Living indoors is not natural so it is important to make natural, non toxic choices when we do so.
We potentially "injest" more toxins in air than from water or food. All must be considered but air is number 1. Of course this speaks to the projected secondary realm of consiounsess that outcrops out of our thinking. If we consider this, and we must, then actually spiritual coherence is the most important consideration of all because out of that pours forth our decisions about air, water and food. Clean the lens and the created reality unfolds coherently in tune.