As the effects of climate change become more visible, water has emerged as a sustainability indicator as critical as carbon. According to UN estimates, global freshwater demand will exceed current supply by 40 percent in 2030. This projection represents a tangible risk to the operational continuity of water-intensive sectors (textiles, food, beverage, chemicals, mining). A water footprint assessment is the measurement, in line with the ISO 14046 standard, of the volume of water consumed and affected by an organisation or product across its life cycle.
The Three-Colour Water Approach
Water footprint is traditionally classified into three colours:
- Blue water: The volume of water withdrawn and consumed from freshwater sources (groundwater and surface water). It is used for agricultural irrigation, cooling, drinking water and process water.
- Green water: Water retained in the soil through precipitation and used in plant growth. It is critical for agriculture and forestry.
- Grey water: The theoretical volume of freshwater required to dilute polluted water generated during production to an acceptable discharge quality. It is a kind of "pollution conversion" indicator.
The ISO 14046 Standard
The ISO 14046:2014 standard, "Environmental Management - Water Footprint - Principles, Requirements and Guidelines", tailors the LCA (Life Cycle Assessment) methodology to water resources. The standard defines two core approaches:
- Stoichiometric (volumetric) approach: The volume of water consumed is expressed in kg or m³.
- Impact approach: The effect of consumption on local water scarcity and the ecosystem is weighted using watershed-based factors. The AWARE (Available WAter REmaining) indicator is the most widely used application of this approach.
Which Sectors Is It Critical For?
For water-intensive sectors, a water footprint assessment is a tool as strategic as the carbon footprint:
- Textiles and apparel (dyeing, washing, raw material production)
- Food and beverage (agricultural raw materials, cooling, cleaning)
- Chemical and pharmaceutical industries (process water, cooling)
- Mining and metallurgy
- Energy generation (thermal power plant cooling, hydroelectric)
- Hospitality and tourism (critical in water-scarce regions on a watershed basis)
Watershed Risk Analysis
A water footprint assessment is not sufficient on its own; the impact of the same litre of water differs entirely across different watersheds. 1,000 m³ consumed in a water-rich region does not carry the same environmental cost as 1,000 m³ consumed in a water-scarce region. For this reason, modern water footprint studies include a watershed-based risk analysis layer fed by tools such as the WRI Aqueduct and the WWF Water Risk Filter.
Unlike carbon, water is a local indicator rather than a global one. The same company consuming the same volume of water at different facilities will cause different environmental impacts.
Integration with CDP Water Security
A water footprint assessment forms the basis of CDP Water Security responses. A water inventory prepared in line with ISO 14046 provides direct data for CDP's questions, while watershed-based risk analysis answers CDP's "physical risk" section. An organisation's mature water management is a prerequisite for a CDP Water A score.
Frequently Asked Questions
- How different is a water footprint assessment from a carbon footprint?
Methodologically it is similar to carbon (LCA-based); however, water is a local rather than a global indicator like climate. The assessment is therefore evaluated using watershed-based scarcity multipliers alongside consumption volume. Whereas 1 tonne of CO2 has the same value everywhere for carbon, each region carries a different "weight" for water.
- Is a water footprint meaningful for non-agricultural sectors?
Yes. Although agriculture is the most intensive in terms of direct consumption, textile dyeing, chemical processes, cooling towers and even data centre cooling have high water intensity. Water management has also become a critical topic in the IT sector in recent years.
- Can a product-level water footprint be reported?
Yes. For consumer products such as a shirt, a glass of water or a packaged food item, information on "how much water was used in production" can be shared on labels. This reporting is carried out as an extension of an LCA study.