WATER FOOTPRINT
The water footprint measures the amount of water used to produce each of the
goods and services we use. It can be measured for a single process, such as
growing rice, for a product, such as a pair of jeans, for the fuel we put in our car,
or for an entire multi-national company.
The water footprint has three components: green, blue and grey. Together,
these components provide a comprehensive picture of water use by delineating
the source of water consumed, either as rainfall/soil moisture or
surface/groundwater, and the volume of fresh water required for assimilation of
pollutants.
Types of Water Footprint
Green water footprint is water from precipitation that is stored in the root zone of the soil and evaporated, transpired or incorporated by plants. It is particularly relevant for agricultural, horticultural and forestry products
Blue water footprint is water that has been sourced from surface or groundwater
resources and is either evaporated, incorporated into a product or taken from one
body of water and returned to another, or returned at a different time. Irrigated
agriculture, industry and domestic water use can each have a blue water footprint.
Grey water footprint is the amount of fresh water required to assimilate pollutants to
meet specific water quality standards. The grey water footprint considers point-source
pollution discharged to a freshwater resource directly through a pipe or indirectly
through runoff or leaching from the soil, impervious surfaces, or other diffuse sources.
Methods for calculating Water Footprint
ISO 14046: Water footprint: Principles, requirements and Guidelines
states all the international standards for
conducting an LCA-based water footprint for products.
In SimaPro, there are 10 methods for calculating the water footprint.
Each method has unique qualities. SimaPro Method manuals helps to
understand these methods.