Water use in agriculture accounts for approximately 70% of global freshwater usage, making it the largest consumer of water resources worldwide. The agricultural water footprint encompasses three distinct types: green water from rainfall, blue water from surface and groundwater sources, and grey water resulting from pollution. With climate change expected to significantly influence crop growth and water availability in the coming decades, understanding how water is used in agriculture, the types of water involved and how to manage water use is essential for building climate resilience.
Global Water Use in Agriculture
The level of freshwater withdrawals in agriculture varies greatly between regions based on economic priorities, climate and how developed each continent is. Agricultural water usage shows striking differences between continents. African and Asian farmers use more than 80% of the available freshwater resources. In Africa, uneven distribution of rainfall across the continent and droughts in arid and semi-arid areas have also contributed to increased freshwater consumption. European agriculture requires significantly less water. Western European farmers use just 5% of their water resources. These differences show how economic development and natural phenomena could shape water usage patterns. A country's income level relates directly to its agricultural water consumption
Source: Food and Agriculture Organization of the United Nations
How is Water Used in Agriculture
The use of water in agriculture goes beyond irrigation; it’s also used throughout the entire food production cycle:
- Irrigation of crops: This is the most common and water-intensive process in agriculture. It includes surface irrigation (flooding), sprinkler systems and more efficient methods like drip irrigation. The type of irrigation used greatly impacts water consumption and efficiency.
- Livestock drinking water and cleaning: Water is required to keep animals hydrated, clean and healthy. Facilities that raise animals for meat, dairy or eggs must maintain hygiene through frequent washing and sanitation, all of which consume substantial amounts of water.
- Post-harvest processing: Once crops are harvested, water is often used to wash, sort and package produce. This step is essential for food safety and shelf life but can be water-intensive without efficient systems in place.
- Cooling and climate control in greenhouses: In controlled environments like greenhouses, water is also used to cool the environment and maintain optimal humidity levels. Evaporative cooling systems, for instance, are major contributors to water use.
- Pesticide and fertiliser application: Water is often used as a carrier for agrochemicals, ensuring even distribution across fields. This practice, however, contributes to runoff and increases the grey water footprint due to contamination.
Types of Water in Agriculture
Agricultural water footprint analysis looks at three basic categories that help us understand water resources in farming systems. These categories make it easier to track different water sources and their effects on the environment. Farmers and policymakers can use this knowledge to create better water management strategies that work in different climate conditions.
Green Water: This is derived from precipitation that infiltrates the soil and becomes available to plant roots. Rainwater stored in the soil and used directly by plants through transpiration. Green water makes up about 78% of the total water footprint in global crop production. Plants get their water from rainfall stored in soil moisture, which is called green water. This concept shows us how important soil water is to agriculture. Green water serves as the main source for all plants that don't require irrigation, such as forests, grasslands and rain-fed crops. As it does not involve water abstraction, green water use is generally viewed as a more sustainable use of water. However, changes in land use or deforestation can reduce green water availability by disrupting the local water cycle.
Blue Water: This is freshwater sourced from surface bodies (rivers, lakes) or groundwater (aquifers) used for irrigation or livestock. Blue water is typically accessed through irrigation systems, wells, canals and reservoirs. It supports intensive agriculture, particularly in arid and semi-arid zones where rainfall is insufficient. The rapid growth of irrigated farming puts huge pressure on the environment, and groundwater pumping for irrigation now leads all other groundwater uses globally. Overuse of blue water can lead to aquifer depletion, reduced river flows and cause ecological degradation. Sustainable use requires monitoring withdrawal rates against recharge capacities.
Grey Water: Grey water in farming refers to freshwater that gets polluted by agricultural activities. It refers to the volume of freshwater required to dilute pollutants (e.g., nitrates, phosphates) to meet water quality standards. Grey water is a metric of the environmental impact of farming practices on water quality. High grey water volumes indicate inefficient input use and pollution. Managing grey water is essential for protecting downstream water bodies. Strategies such as precision fertilisation and constructed wetlands can help reduce this footprint. Grey water can also be sent to water treatment facilities for purification.
Water Footprint Assessment in Agriculture
A water footprint assessment is a comprehensive method of evaluating the volume and impact of water used across agricultural supply chains. It helps companies in measuring and managing their water footprint in compliance with ISO 14046. This considers:
- Direct water use: This includes all on-farm water uses, such as irrigation, animal care, and processing. It helps quantify operational efficiency and reveals opportunities for saving water.
- Indirect water use: Refers to water embedded in inputs like feed, seeds, fertilisers and pesticides. Understanding this "virtual water" footprint is essential for full supply chain transparency.
- Water pollution and waste discharge: The assessment calculates how much water is required to assimilate pollutants, providing insight into environmental degradation and compliance risks.
Water footprint assessments help businesses:
- Identify hotspots of water overuse: Pinpointing where in the production cycle water demand is highest allows for targeted interventions.
- Understand dependencies on water-stressed regions: Mapping water use against geographical risk helps businesses manage exposure to droughts, regulation and supply chain disruption.
- Improve resource efficiency: By optimising irrigation and input application, farms can reduce waste, costs and their environmental footprint.
- Enhance supply chain sustainability: Demonstrating responsible water use supports customer expectations and retailer procurement policies.
- Support regulatory compliance: Standards like ISO 14046 and frameworks like the Science Based Targets for Nature increasingly require robust water accounting.
The Importance of Monitoring Water Use in Agriculture
Improving water efficiency is a strategic business move for sustainability in the agricultural sector. Key benefits include:
Enhanced resilience to climate variability: Better planning in water use makes operations more adaptable to extreme weather events.
Improved stakeholder and investor confidence: Transparent water reporting demonstrates proactive ESG management, attracting values-driven partners.
Compliance with sustainability frameworks: Aligning with initiatives like CDP Water, GRI Standards and the UN SDGs supports procurement requirements and brand reputation.
Support for ESG and Net Zero targets: Water efficiency often correlates with energy savings, helping to meet broader climate goals.
The Bottom Line
Climate change poses a real threat to farming water supply through more floods and droughts. Sustainable water use in agriculture encompasses knowing just how much water is used, the types of water and its impact on the environment. By implementing water footprint assessments, optimising irrigation strategies and reducing pollution runoff, agricultural producers and food companies can significantly reduce their environmental impact while improving operational resilience. Tunley Environmental’s Water Footprint Assessment service offers tailored insights to support better water management.