You could say that water makes the world go ‘round. It’s more than just a necessity for health and hydration, it’s needed for agriculture and industrial production as well. In fact, over two-thirds of global water use is agriculture related, even for things that might not seem obvious at first glance.
At a global scale, the biggest consumer is agriculture, which accounts for roughly 70%. Next, industrial uses make of 20% of world consumption, and domestic use is around 10%.
Water use varies widely around the world. In the United States, the average person uses 1,582 cubic meters of water per year for sanitary and household tasks, whereas the average German uses just 311 cubic meters. This difference is due in large part to variations in household consumption habits and appliances (American toilets flush with greater amounts of water than most European toilets, for example).
The average shower uses between 30 and 80 liters of water, while running a bath requires between 150 and 200 liters. Flushing a toilet uses anywhere between 10 and 15 liters. A dishwasher cycle is generally between 13 and 21 liters, but doing the dishes by hand brings water consumption down to between 5 and 15 liters!2
Individual water use in developing countries, on the other hand, is generally much lower than in wealthier ones: the average African family uses less than 20 liters of water per day for household tasks.
Consumers can directly affect their water footprint by adjusting their household habits—i.e., taking shorter showers or buying more efficient appliances. However much of the water use an individual person is responsible for is not related to direct household use, but rather shows up as “virtual water.” That is, water used in the production of food and consumer goods.
Because agriculture is the single largest use of water, countries with large agricultural sectors—like the United States, China, India, Brazil, and France—thus have larger “water footprints.”
Within agriculture uses for water, certain products are more water intensive than others. Cattle destined to become beef are notable for requiring very large quantities of water—every gram of beef requires 112 liters of water to produce. Likewise, growing a kilogram of cotton or a kilogram of rice both require over 5,000 liters of water, whereas a kilo of wheat takes 590 liters, a kilo of bananas requires 350 liters, and a kilo of corn (in a temperate climate) is relatively water efficient to grow, at 240 liters.
And for certain agricultural products, geography matters as well. For example, the amount of water required to grow corn, potatoes, and wheat differs in temperate climates compared with tropical climates. This is because in hot and sunny climates, some crops require greater and more frequent irrigation.
When it comes to industry, wide variations in water use are also observable. It takes 75 liters of water to make a single glass of beer when the water footprint of its component ingredients is taken into account. It even requires a lot of water to produce things that don’t actually contain any water: between 300 to 600 liters of water to produce a kilogram of steel, around 500 liters to produce a kilo of paper, and 35 liters for a kilo of cement.
Water usage for industrial production tends to vary more depending on exactly what is produced than where production occurs. However, in terms of an individual country’s water footprint, the role of industrial production can vary greatly. For example, Belgium has the highest percentage of its national water footprint that comes from industry, at 41%. Whereas in most African countries, industry makes up a relatively small percentage of the overall water footprint (it’s highest in Nigeria, where the water footprint is roughly split between household, industrial, and agricultural use, but industrial use is far lower in South Africa, Senegal, and Madagascar).
Looking to the future
Because climate change is increasing the number of “water-stressed” regions in the world, and with urbanization placing greater demands on water resources, sustainable water management is a challenge that must be met by all stakeholders, including policymakers, industry, agriculture, and consumers. Good water stewardship places importance on the local context of every watershed, and then engages in meaningful individual and collective action to promote sustainability.