Other than air, nothing is more directly and immediately important to life than water. Water is so basic to our existence that in antiquity the ancients considered water an element along with air, fire and earth.

The ancients were not far wrong. Water is unique. Water exists as a solid, liquid and gas at normal atmospheric and temperature conditions at the surface of the Earth. Few substances have this capacity and none composes as large a part of the Earth. This marvelous ability of water to move between these three physical states allows for the hydrologic cycle of water vapor rising and then condensing in the atmosphere causing rain to fall to the land, collecting and running down to rivers, lakes or the ocean and evaporate again restarting the cycle.

The ability of water to dissolve solids, liquids and gases into itself makes it a universal solvent. Few substances other than water are universal solvents and those that are, such as alcohol and benzene are toxic to carbon based organic life forms.

The ability of water to dissolve solids and liquids allows it to carry food to the cells in our body and carry away the wastes generated in the life process. Fortunately, as excellent a solvent as water is, it does not dissolve calcium or phosphorous, otherwise our bones would liquefy. One fact we all learn at an early age is that 70% of our body is composed of water. A loss of water from our bodies, even as slight as 12%, can mean death.

If water did not dissolve gasses, there could be no aquatic life as they ‘breath’ dissolved oxygen directly from water. The capacity of water to dissolve substances changes as its temperature changes. As water heats up most solids and liquids dissolve more easily in water. However, gasses such as oxygen dissolve less easily in warmer water. If water is too warm, dissolved oxygen levels drop below requirements for aquatic life.

Water is composed of hydrogen and oxygen, but the bond between these two elements is unusual. Once water forms, there remains a little extra bonding power left over and water molecules form hydrogen bonds with other water molecules. Each molecule of water is attracted to and holds onto any water molecule near it. This extra bonding power means that one could think of a beaker of water, a lake or for that matter an ocean as one single assemblage of water. The extra bond also means that water is inelastic so it does not compress and is why a “belly flop” dive hurts and why fish have developed their elongated and tapered shape that allows them to cut through the water not try to push against it.

Water is one of the few substances found anywhere in nature that expands as it freezes and that expansion means ice weighs roughly 90% the weight of liquid water. Given that water is densest just before it freezes, ice floats on water so lakes and rivers freeze from the top down not from the bottom up. If it were otherwise, aquatic creatures living in cold climates could not exist. An ice-encrusted bottom would mean that water could not flow under and around the rocks and cobble on the bottom of water bodies depriving aquatic organisms of oxygen and food. Anchor ice does form occasionally on small stream bottoms, unfortunately that means there is no possibility of life on that bottom.

With three-quarters of the earth covered by water, it would seem there is more than enough for all of us and other species. Consider though, before one jumps to that conclusion, if the 7.3 billion people on the earth divided the 335 sextillion (1021) gallons of water on the earth there would be 46 billion gallons of water for every person. However, out of each person’s ration 97.4% is salt water. Of the remaining water that is fresh water, 98% of it is ice in the Greenland glaciers and the polar ice caps. That still leaves a goodly amount of liquid fresh water for each person but water is not uniformity spread throughout the world and much of it after our tampering with it is unusable for consumption.

Everything water does for us, water does for all other species. Their lives, like ours, cannot continue without clean water. As the single species wielding the power to destroy worldwide habitat, our responsibility to insure the existence of other species means we humans have a special responsibility to water.

We will not see any more water on the Earth than we have right now so we should not be complacent just because it is a substance found everywhere around the Earth. We need to protect and cherish the wonder substance, water.

David L. Deen is Upper Valley River Steward for the Connecticut River Watershed Council. CRWC is celebrating over 60 years as a protector of the Connecticut River.