Problems in Supplying Pure Drinking Water

Of all the necessities of life, few are so fundamental as water. Yet on a thirsty planet with a fast-growing population, clean water is often in short supply. According to a World Health Organization study from 2005, some 1.1 billion people --- roughly a sixth of the human population --- lack access to safe clean drinking water. This problem stems from several root causes.

Global Availability

• About 97.5 percent of the water on the earth's surface is in the oceans, according to "Essential Environment" authors Jay Withgott and Scott Brennan. That leaves only 2.5 percent of fresh water. Of that 2.5 percent, 79 percent is frozen in ice caps and glaciers, and 20 percent is groundwater. A mere 1 percent is surface fresh water (e.g., rivers and lakes).

Climate Variation

• Variations in climate mean that available fresh water is unevenly distributed across the earth's surface. For instance, Canada has roughly 20 times more fresh water per capita than China, while Iceland has 100 times more fresh water per capita than Somalia or Pakistan.

  These disparities mean that some of the world's most populous nations lack water, while others have more than they need. Furthermore, local droughts can exacerbate shortages in regions already cursed with a limited supply of fresh water. In wealthier areas like California, a drought may entail water rationing, and damage local economies by increasing the cost of doing business. In poorer nations like Ethiopia, however, drought can wreak havoc with crop yields and cause famine, illness and death.

Wealth Disparities

• Poor nations usually cannot afford expensive options like desalination, which may be available to wealthy first-world nations. Also, environmental regulations in poorer countries are often lax or loosely enforced, because governments lack the resources to impose and enforce stronger regulations.

  According to a 2007 article in Smithsonian magazine, for example, the amount of domestic sewage released into India's Ganges River has doubled since the 1990s, and the regulatory status of industrial polluters has changed little over the past two decades. Water polluted with sewage and industrial chemicals is unfit to drink unless municipalities treat it to remove contaminants; however, water-treatment facilities may be inadequate in many poorer countries, or absent altogether.

Unsustainable Extraction

• Humans are depleting freshwater resources at an unsustainable rate. As populations in dry and arid regions increase, the demand for water increases while the supply remains constant. For example, the demand for Colorado River water is so great that only a trickle of the water currently reaches the sea. Regardless, demand for Colorado River water is increasing.

  Similarly, the Aral Sea has lost about four-fifths of its volume in 40 years, largely due to the increasing demands of agriculture. Alternatives like seawater desalination and indirect potable reuse are expensive, and may be politically unpopular.