At the international level, water conflicts among countries dominate the headlines. But within countries it is the competition for water between cities and farms that preoccupies political leaders. Neither economics nor politics favors farmers. They almost always lose out to cities.

Indeed, in many countries farmers now face not only a shrinking water supply but also a shrinking share of that shrinking supply. In large areas of the United States, such as the southern Great Plains and the Southwest, virtually all water is now spoken for. The growing water needs of major cities and thousands of small towns often can be satisfied only by taking water from agriculture. As the value of water rises, more farmers are selling their irrigation rights to cities, letting their land dry up. Read more

When you’re wading in a cool mountain stream, and you can see your to­es in the sand, you assume the water’s safe to drink. But even water that looks perfectly clear may harbor a variety of bacteria, parasites and protozoa that can make you very ill. You can’t tell from smelling or taking a small taste whether water is safe to drink. Even water from spigots in campgrounds may not be. When you’re camping, unless there’s a sign that specifically states that water is safe to drink, you should take precaution and treat it.

Portable water filters are probably the easiest and safest way to treat water for drinking. There are many choices in water filters. The least expensive may cost less than $20, while more expensive filters can cost several hundred. For the average user, it’s possible to find a perfectly functional water filter for less than $100. Read more

There’s a whole lot of water on Earth! Something like 326,000,000,000,000,000,000 gallons (326 million trillion gallons) of the stuff (roughly 1,260,000,000,000,000,000,000 liters) can be found on our planet. This water is in a constant cycle — it evaporates from the ocean, travels through the air, rains down on the land and then flows back to the ocean.

The oceans are huge. About 70 percent of the planet is covered in ocean, and the average depth of the ocean is several thousand feet (about 1,000 meters). Ninety-eight percent of the water on the planet is in the oceans, and therefore is unusable for drinking because of the salt. About 2 percent of the planet’s water is fresh, but 1.6 percent of the planet’s water is locked up in the polar ice caps and glaciers. Another 0.36 percent is found underground in aquifers and wells.

Only about 0.036 percent of the planet’s total water supply is found in lakes and rivers. That’s still thousands of trillions of gallons, but it’s a very small amount compared to all the water available. Read more

In its purest form, it’s odorless, nearly colorless and tasteless. It’s in your body, the food you eat and the beverages you drink. You use it to clean yourself, your clothes, your dishes, your car and everything else around you. You can travel on it or jump in it to cool off on hot summer days.

Many of the products that you use every day contain it or were manufactured using it. All forms of life need it, and if they don’t get enough of it, they die. Political disputes have centered around it. In some places, it’s treasured and incredibly difficult to get. In others, it’s incredibly easy to get and then squandered. What substance is more necessary to our existence than any other? Water.

At its most basic, water is a molecule with one oxygen atom and two hydrogen atoms, bonded together by shared electrons. It is a V-shaped polar molecule, which means that it’s charged positively near the hydrogen atoms and negatively near the oxygen atom. Water molecules are naturally attracted and stick to each other because of this polarity, forming a hydrogen bond. This hydrogen bond is the reason behind many of water’s special properties, such as the fact that it’s denser in its liquid state than in its solid state (ice floats on water). We’ll look closer at these special properties later. Read more