A precious good

More than two-thirds of the earth's surface is covered with water. But only a fraction of it - about 3 percent - is fresh water. With the world's population growing fast, the water supply is coming under increasing pressure. Around the world, 2 billion people already have no safe access to drinking water.

Another 2 billion people live in areas suffering from water scarcity. That number is set to rise in the coming years due to climate change. By 2050, 3 billion people are projected to live in areas that are too dry.

The United Nations has been drawing attention to this threat for the last 25 years. Every year on March 22, the organization celebrates World Water Day. Each year, the day has a different motto. For 2018 it is "Nature for Water" - aiming to draw attention to nature's own solutions to drought, flooding, and pollution.

Another, manmade solution is to reuse wastewater. If properly treated, it can be a very efficient source of fresh water and help protect natural sources from over-use. Still, the process is complicated and expensive and few countries can afford it.

In Israel, 90 percent of wastewater is reused, in part for agricultural irrigation. However, most countries do not yet have the capacity to take advantage of this resource. Worldwide, 80 percent of the wastewater goes back to nature untreated and ends up polluting the water bodies as a result.

Properly processed wastewater could also help to alleviate the scarcity of drinking water. Namibia and Singapore already reuse purified wastewater as drinking water. In many other countries, however, there are reservations. People fear they will get sick from drinking water that has not been cleaned well enough.

People often see bottled water as a healthier alternative to what comes out of the faucet. But recent studies have shown that pollutants get into the bottles too. Tiny bits of plastic have been found in many brands of bottled water throughout the world. One possible source is the plastic bottles themselves.