The water footprint of one pound of cotton is 1,320 gallons. In fact, it takes at least twice as much water to produce a plastic water bottle as the amount of water contained in the bottle. For example, it takes 22 gallons of water to make one pound of plastic. Similarly, water is consumed in manufacturing most other products. The Water Footprint of Everyday Paper, Plastic and Cotton When the water required for all the steps to make a smart phone is added up, the water footprint of the production of a single phone is an estimated 3,190 gallons. The water used to clean and dilute the wastewater adds up to the grey water footprint, and in the case of the smartphone, makes up the largest portion of its total water footprint. Those waterways often have pollution limits that manufacturers must meet before they can send their wastewater down the pipe and into the waterway. In addition, manufacturing the parts creates wastewater that is released into surrounding waterways. Collectively, the water associated with each step adds up to the blue water footprint. Production might include steps like mining for precious metals, creating synthetic chemicals for glue and plastic and assembling and packaging. The supply chains for these materials stretch around the world to places like Indonesia, the Philippines and China. Numerous resources, materials and parts go into smartphone manufacturing, including rare earth metals (e.g., lithium), tin, glass and plastics. Phones are composed of many pieces created in multiple steps, and each step consumes water. Their water footprint comes from the virtual water associated with their manufacturing – what’s known as the “ grey water footprint.” How Much Virtual Water is in a Smartphone? Grey Water Footprint: The amount of freshwater required to dilute the wastewater generated in manufacturing, in order to maintain water quality, as determined by state and local standards. Green Water Footprint: The amount of rainwater required (evaporated or used directly) to make an item. The Water Footprint Network (whose research provides some of the data used in the WFC) defines these components as:īlue Water Footprint: The amount of surface water and groundwater required (evaporated or used directly) to produce an item.
Sources: Berger et al Water Footprint Network, “Water footprints of nations” Friends of the Earth/Trucost WFN, “The water footprint of cotton consumption” WFN, “The water footprint of wood for lumber, pulp, paper, fuel and firewood” TABLE: Data compiled, converted and produced by Water Footprint Calculator. Water Footprint of Common Consumer Items. The water footprint of a product is calculated by adding up all of the water required for each step of the production process. Table 1 lists a sampling of water footprints for the manufacturing of some common consumer goods. Hidden water is water that is not felt or seen and it is required for almost every step in the production processes for many raw materials and finished products.
Hidden Water: How the Water Footprints of Consumer Goods are Calculated Knowing how much water it takes to make the raw materials and products we all use and consume is an important first step towards water conservation and using water more productively. Manufacturing everyday materials like paper, plastic, metal and fabric takes water – a lot of it. It may not be visible, but millions of gallons of virtual water go into making the consumer goods Americans buy, use and throw away. Hidden water is an important part of water use.
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