MENLO PARK, Calif.--How much water does it take to make a pair of leather shoes? Eight-thousand liters.
That's from Hans Enggrob, head of innovation at the DHI Water Group, a research and consulting firm, speaking at the Nordic Green conference taking place this week at SRI International's offices here.
It takes 2,000 liters to make a cotton T-shirt, 2,400 liters to make a hamburger, and 1,200 liters to produce a gallon of ethanol, he said.
But beer drinkers should rejoice. It only takes 75 liters for a glass of beer and 140 liters for a cup of coffee, he added. Much of the water in these products goes toward irrigating crops used to make these products.
Enggrob, like many others, points out that the world is facing a pending water crisis. Several start-ups concentrating on water purification and desalination have received funding in recent years and large giants such as General Motors have put more emphasis on water. Still, demand is growing faster than supply. China, Australia, and several African nations are already grappling with water shortages. In the U.S., some believe Lake Mead could run dry by 2021.
In the middle of the 20th century, there was about 4,000 cubic meters of fresh water per person per year, Enggrob said. Now we're close, globally, to 1,000 cubic meters per person per year. One thousand cubic meters per person per year is defined as water scarcity, he said. Water stress is defined as having 1,700 cubic meters per person per year.
Most countries also have to update their regulations and municipal water systems with regard to water reuse and purification. Singapore's NEWater, which constitutes part of the water coming out of the taps there, is actually reprocessed water from the sewer. Japan and Dubai make somewhat extensive use of gray water. But most jurisdictions haven't gone that far.
Purification is the bright spot in water. When oil is burned, the molecule is consumed, forcing humans to look for more. Water gets polluted but it can be cleaned.
"We have pretty much the same amount of water that we had four billion years ago," said Paul Frederiksen, head of research at Grundfos, a Danish company specializing in energy-efficient pumps.