Five myths about water

Water is the most familiar substance in our lives, and the most important. Every cell in our bodies is plumped full of water; every heartbeat, every thought — including thoughts about water — happens only because of the cascade of chemistry that water makes possible. Yet we know almost nothing about water, starting with such basics as: Where does our water come from? Where does it go once it disappears down the drain? In fact, even what we think we know about water is often wrong.

1. We’re running out of water.

We see it in the headlines almost every day: Drought in Texas and China. Nevada’s Lake Mead in danger of going dry. The Colorado River and the Rio Grande no longer flowing to the sea.

Five Myths

A feature from The Post’s Outlook section that dismantles myths, clarifies common misconceptions and makes you think again about what you thought you already knew.

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Fact or fiction?: A collection from Outlook’s popular Five Myths series.

Water seems to be getting more and more scarce. But it’s not. The amount of water on Earth isn’t changing, and as a planet we’re in no danger of running out.

One of the most misleading “facts” we learn about water, starting in the second grade or so, is that 97.5 percent of the water on Earth is unusable by humans, because it’s salty ocean water.

Actually, the oceans are Olympian springs of fresh water — every day, the sun, the sea and evaporation combine to make 45,000 gallons of rainwater for each man, woman and child on Earth. Even in the United States, where we use water with profligacy, the oceans are making more fresh water for each of us in a month than we’ll use in a decade.

And one of the most remarkable qualities of water, of course, is that we never really use it up. Water reemerges from everything we do with it, whether it’s making coffee or making steel, ready to use again.

The problem is that we’ve built our communities, our farms and our reservoirs in places we expect water to be. The scarcity we’re seeing is a result, in part, of a shifting climate — it’s still raining, but it may not be raining in the watersheds of our reservoirs. Water scarcity is also a result of population growth; more people need more water. And it is often a hidden cost of economic development. As people get wealthier, they use more water for things such as bathing and running the dishwasher, and more energy, which requires huge volumes of water.

2. Bottled water is better than tap water.

Tap water in the United States is among the safest in the world. And it is much more closely monitored than bottled water. Cities must test their water every few hours and report any safety issue within 48 hours. Bottled-water companies are required to test their water only once a week, and they are not required to report problems.

Occasionally, there are issues with municipal water in the United States. The presence of lead in some parts of Washington’s water system is a vivid example. But those exceptions underscore how important safe water is and how rare problems are.

Anyone who is worried about safety should use a commercial faucet or pitcher filter. And anyone who thinks tap water tastes bad compared with bottled water should remember that you usually buy bottled water from a cold case, when you’re really thirsty. That’s why it tastes so great. Keep a pitcher or bottle of tap water in your refrigerator, and it will taste just as good as bottled water. In fact, in blind taste tests, people can’t reliably pick bottled from tap.

3. This is going to be a century of water wars.

Although we hear all the time that “water is the next oil” — that it will become a source of international conflict, that its price will soar — there aren’t likely to be water wars anytime soon.