A water footprint measures the total volume of freshwater used to produce goods or services, encompassing all water consumed and polluted throughout a product’s entire lifecycle. A pair of jeans carries a substantial water footprint, from raw materials to consumer use.
The Water-Intensive Journey From Cotton to Fabric
Jeans are primarily made from cotton, a natural fiber known for its high water requirements during cultivation. Growing one kilogram of cotton, which is roughly enough for a t-shirt and a pair of jeans, can require anywhere from 7,000 to 10,000 liters of water, though some estimates for less efficient practices go up to 20,000 liters. In regions where cotton is grown, much of this water comes from irrigation, often depleting local surface and groundwater sources. This heavy reliance on irrigation places considerable strain on freshwater availability, particularly in arid and semi-arid climates where cotton is frequently cultivated.
Beyond water quantity, cotton farming also impacts water quality. Conventional cotton production often involves the extensive use of pesticides and fertilizers. Runoff from cotton fields can carry these chemicals into rivers, lakes, and aquifers, leading to water contamination and harming aquatic ecosystems. Such pollution can cause issues like eutrophication, where excess nutrients lead to algal blooms that deplete oxygen in water bodies.
After harvesting, cotton undergoes processes to be spun into yarn and then woven into denim fabric. These initial stages also require water, although the most significant water usage remains in the agricultural phase. Transforming raw cotton into the sturdy denim material sets the foundation for the extensive water demands that continue through the subsequent manufacturing steps.
Manufacturing’s Thirsty Processes
Once the denim fabric is created, its transformation into finished jeans involves several water-intensive manufacturing processes. Dyeing, especially the iconic indigo dyeing, uses large volumes of water. This stage also introduces chemicals and dyes into the water, which can become polluted wastewater if not properly treated.
Various finishing treatments further contribute to the water footprint. Processes like stone washing, acid washing, bleaching, and distressing are applied to achieve specific looks and textures. Stone washing a single pair of jeans can require approximately 70 liters of water. These finishing techniques often employ pumice stones, chemicals like potassium permanganate, and other agents that necessitate significant water for rinsing and can result in contaminated effluent.
The chemical-intensive nature of these manufacturing steps not only consumes vast amounts of water but also poses a considerable challenge for wastewater treatment. Untreated discharge can release hazardous substances and dyes directly into the environment.
Understanding the Types of Water Footprints
The total water footprint of a product like jeans is comprised of three distinct components: green, blue, and grey water. Green water refers to the rainwater stored in the soil that is evaporated from crops. For jeans, this primarily accounts for the natural rainfall absorbed by cotton plants.
Blue water is freshwater sourced from surface or groundwater, such as from rivers, lakes, and aquifers, used in production and either evaporated, incorporated into the product, or returned to a different body of water or at a different time. This category includes irrigation water used in cotton cultivation, which forms a large part of the jean’s overall water footprint. It also encompasses the water used in various factory processes, such as dyeing and finishing.
Grey water represents the volume of freshwater required to assimilate the load of pollutants to meet specific water quality standards. This includes the water needed to dilute chemicals and dyes discharged during manufacturing processes, particularly from dyeing and finishing, to a level that is not harmful to the environment. Understanding these different types provides a comprehensive view of the water impact throughout the lifecycle of a pair of jeans.
Consumer Habits and the Water Footprint
The water footprint of jeans extends beyond their production and into their post-purchase life, largely influenced by consumer habits. Each time jeans are washed at home, additional water is consumed by washing machines. The frequency of washing significantly adds to the overall water footprint of the garment.
Furthermore, synthetic blends in jeans can shed microplastic fibers during washing. These tiny plastic particles can enter waterways and ecosystems, contributing to pollution.
Making a Difference
Manufacturers are increasingly adopting innovative approaches to reduce the water footprint of jeans. Some companies are implementing waterless dyeing techniques, such as air-dyeing and foam dyeing, which can drastically cut water usage by up to 90%. Laser finishing and ozone treatment are also being used to achieve distressed looks with significantly less water and chemicals compared to traditional methods. Many facilities are investing in closed-loop water recycling systems, allowing them to treat and reuse up to 90% of the water in their manufacturing operations.
Efforts are also underway in the agricultural sector to promote sustainable cotton farming practices. These include using more efficient irrigation methods like drip irrigation, which can reduce blue water demand by 35-65%, and transitioning to organic farming that minimizes the use of water-polluting pesticides and fertilizers. Consumers can also contribute by washing jeans less frequently, choosing cold water washes, and line drying to save water and energy. Opting for second-hand jeans, repairing existing pairs, and selecting brands committed to sustainable practices are other ways individuals can help reduce the overall water impact of their denim.