Water footprint means the amount of freshwater used and polluted to avail of a service or to produce a product. The extent of water that we use can be measured. It can be estimated for an individual, a multinational company, a population living in a river basin, or a country.
Since sources of water are fast depleting, it has become essential to trace the water footprint of the product used, or service availed. Uses of water are unfathomable, and the benefits of water cannot be exhaustively listed.
With depleting sources of water, it has become pertinent to take measures to save water. Before embarking on saving water, we need to understand how much water is used for a particular product or service. The measure of such use is a water footprint.
Water footprint takes into account both direct and indirect use of water in a product or process of a company or individual. It traces water consumption and includes pollution right from production, supply chain to end-user.
The water footprint can be measured for the single production of a pair of jeans or processes like water used in a paddy field. The water footprint is measured in a cubic ton of production per hectare of cropland per unit of currency or other functional units.
Factors contributing to water footprint
There are 4 direct contributors to the water footprint of a nation. These are
• Consumption: Higher the volume of waste, the higher the use of water to produce products and provide services. The water footprint is directly related to the gross national income of the country.
• Consumption pattern: Foods based on animal products uses more water; therefore, the water footprint is higher where meat is consumed more.
• Climate: Climate change affects crop production and development. Less rain entails more dependence on already stressed freshwater resources
• Agricultural practice: cultivation dependent on rainwater or irrigation facilities like canal irrigation, tanks, wells, etc., a large amount of water is lost. Water flows out, taking with it top fertile soil. Lots of water is lost using the modern method of sprinkler irrigation as much water gets evaporated before reaching the earth. The best way to irrigate is drip irrigation. Water is supplied directly to the roots of the plants using pipes. However, the cost of installing pipes and maintaining it is costly.
Elements of the water footprint
The concept of water footprint was used to improve water management. The water footprint of a product or a service is divided into three parts. Each of these parts is identified by the colors green, blue, and grey.
• The green element of water footprint means water consumption contained in plants and soil. Here water consumption is not in surface waterbodies nor underground water bodies. Rainwater is a green element when it does not percolate underground to collect in an aquifer. Rain in roots of soil, which may evaporate transpired or incorporated by plants, is the green element. This is relevant for agriculture, horticulture, and forestry.
• A blue part of the water footprint means the volume of surface or groundwater used, evaporated, and incorporated to produce a product or provide a service. Water does not return to the source. Water may be used from one source and returned to another source. It may also happen that water may be returned to the same source but at different times.
• A Grey element of water footprint means the amount of fresh water needed to dilute the pollutants to meet water quality standards. This pollutant is produced as a result of the production of a product or discharge of service. A grey water footprint considers pollutants directly discharged into water resources through pipes, leaching from the soil, runoff, or other impervious means.
Calculation of water footprint
- The method used for calculation for all kinds of water footprint is one single process step.
- The water footprint of a product is the sum of the water footprint used to produce a product, including whole production steps and supply chain.
- The water footprint of a consumer is the total sum of the water footprint of all the products and services used.
- The water footprint of a community is the sum of each member of the community’s water footprint.
- The water footprint of a business is the total water footprint of finished products that the industry produces.
- The water footprint of a nation is the sum of the water footprint of its inhabitants.
- The green water footprint is calculated by taking into account the volume of rainwater used during production
- The grey water footprint is calculated by dividing pollutants in the water body by ambient water quality standard.
Tracing water footprint in some industries
Water footprint in agricultural industries:
Agriculture, being water-intensive, is bound to have the most significant water footprint. Crops that leave huge water footprint per ton of crop are sugar crops, vegetable roots, and tubers, cereals, oil crops, pulses. The water footprint of different food crops is different.
The water footprint also changes from region to region. It also changes with rain-fed or irrigated crops. Rice and wheat have the most significant water footprint, as vast amounts of fresh water are used to produce them.
China, India, and the USA are the largest producers of these crops; therefore, they share a more extensive water footprint. Most of the production of these crops are concentrated in the Indus and Ganges river basin, so the water footprint of these basins are more.
Water footprint in Meat production
Since large quantities of grass and grains are required to raise cattle, the water footprint of meat is much more than crop production. Animals raised by grazing methods have a larger water footprint than those built in the industrial system.
Animals raised in an industrial order or mixed systems have lesser water footprint because their feed is concentrated with lesser roughage, they move less, they are bred to grow faster and are slaughtered at a younger age. The green water footprint for animals raised in the grazing system is more. However, the blue and grey water footprint for pork, beef, and poultry are more or less the same.
Reducing water footprint
Water footprint measures only water consumed from freshwater resources, which is water that is not returned to its source. Some of the following steps can be taken to reduce water footprint to alleviate water stress:
Cap on water footprint:
Governments can put a cap on the amount of water footprint that the industry can produce. Water footprint permits can be issued to keep a check on it. This will put a cap on water consumption in the catchment area of the river basin. The lid can be varied according to the season and keep the river’s minimum volume in the river to maintain river ecology.
Best available techniques, technology, and processes need to be used to reduce water footprint.
Countries like the USA and Europe have a larger water footprint than the global average. So an equitable water use needs to be promoted to reduce water footprint.
People have to be educated to reduce their water consumption and the use of technology to mitigate water scarcity and reduce water footprint.