Overview

Principles, requirements and guidelines for water footprint assessment based on life cycle assessment, covering products, processes and organizations

ISO 14046:2014 specifies principles, requirements and guidelines for water footprint assessment of products, processes and organizations, based on life cycle assessment. It was published in 2014 by ISO/TC 207/SC 5 and remains the current edition. It applies to standalone water footprint studies as well as to water footprint assessments that form part of a comprehensive LCA.

The standard's central methodological insight is that a water footprint is an impact assessment, not a volume count. Simply totalling litres consumed says little, because the environmental significance of water use depends on where and when it occurs: a cubic metre withdrawn from a water-scarce basin is not equivalent to one withdrawn from a water-abundant one. ISO 14046 therefore requires that water use inventory data be linked to the local conditions of the catchment and translated into potential environmental impacts.

Consistent with that, the standard makes an important reporting rule explicit: results shall not be reported as a single number unless the study addresses only a single impact category. A "water footprint" that mixes scarcity, eutrophication and toxicity into one figure is not a conforming result. Studies must be clear about which impact categories are covered, and a study that addresses only some categories must be reported as such.

The methodology follows the four LCA phases of ISO 14040 and ISO 14044: goal and scope definition (including the functional unit, system boundary, spatial and temporal resolution, and the impact categories chosen), water footprint inventory analysis (water withdrawal, consumption, release, quality changes and the form of water — surface, ground, rain), water footprint impact assessment (covering availability-related impacts such as water scarcity, and quality-related impacts such as eutrophication, acidification, ecotoxicity and thermal pollution), and interpretation, with completeness, sensitivity and consistency checks.

Spatial and temporal detail is required to a degree unusual in LCA, because impacts depend on catchment conditions and seasonality. In practice, characterization factors from published methods — most commonly AWARE (Available WAter REmaining), developed by the WULCA working group — are used to convert consumption data into scarcity-weighted results. Those methods are external to the standard; ISO 14046 sets the rules a method must satisfy rather than mandating one.

Reporting requirements cover the goal and scope, inventory and impact assessment results, methods and characterization factors used, assumptions, limitations, and the geographical and temporal coverage of the data. Critical review is required for water footprint studies intended for comparative assertions disclosed to the public, following the ISO 14044 approach.

ISO 14046 is not a certifiable management system standard; a study is verified or critically reviewed, and organizations are not certified against it. Organizations that want a certifiable environmental management system use ISO 14001, and typically use ISO 14046 results as input to environmental objectives, water stewardship programmes and disclosure to frameworks such as CDP Water Security.

Purpose

To specify how to conduct and report a water footprint assessment based on life cycle assessment, so that water-related environmental impacts of products, processes and organizations are quantified with proper regard to local water conditions.

Key Benefits

• Establishes water footprint as an impact assessment rather than a simple volumetric total
• Requires spatial and temporal resolution so results reflect catchment scarcity and seasonality
• Prevents misleading single-number claims unless only one impact category is assessed
• Covers both availability-related and quality-related water impacts
• Applies to products, processes and whole organizations
• Built on the ISO 14040 and ISO 14044 methodology, so it integrates with existing LCA work
• Identifies water hotspots in supply chains, which are often upstream of the reporting organization
• Supports water stewardship programmes and disclosure to investor and customer frameworks
• Provides a defensible basis for water-related environmental claims
• Compatible with published characterization methods such as AWARE

Key Requirements

• Define the goal of the water footprint assessment, including intended application and audience
• Define the scope, including the product, process or organization assessed, the functional or reporting unit and the system boundary
• State which impact categories are included, and identify the study as addressing a single category where that is the case
• Specify spatial and temporal resolution appropriate to the water bodies and catchments involved
• Compile inventory data on water withdrawal, consumption, release and changes in water quality
• Distinguish water types and sources, including surface water, groundwater and rainwater
• Apply characterization models and factors that reflect local water availability and quality conditions
• Assess availability-related impacts such as water scarcity, and quality-related impacts such as eutrophication and ecotoxicity
• Do not report results as a single number unless only one impact category is addressed
• Interpret results with completeness, sensitivity and consistency checks
• State assumptions, limitations, data quality and geographical and temporal coverage in the report
• Follow ISO 14044 reporting requirements where the water footprint forms part of a comprehensive LCA
• Conduct critical review for studies supporting comparative assertions disclosed to the public
• Do not present a water footprint study as certification of the organization

Who Needs This Standard?

Water-intensive manufacturers — food and beverage, agriculture, textiles, paper, chemicals, mining, semiconductors and power generation — plus sustainability teams reporting water impacts, procurement teams assessing supply chain water risk, and LCA practitioners extending studies to water.

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