Water Footprint Assessment is a four-phase process that quantifies and maps green, blue and grey water footprints, assesses the sustainability, efficiency and equitability of water use and identifies which strategic actions should be prioritised in order to make a footprint sustainable.
Water Footprint Assessment is versatile and can inform a broad range of strategic actions and policies from environmental, social and economic perspectives.
These are the four phases of Water Footprint Assessment:
A Water Footprint Assessment begins with setting the goals and scope of the water footprint study. Water Footprint Assessment can be undertaken for diverse purposes.
For example, it can be undertaken to:
A Water Footprint Assessment can be tailored to meet the goals and scope of the study. The goal of the Water Footprint Assessment clarifies what you will do in the subsequent steps: accounting, sustainability assessment and response formulation. The scope of the assessment defines the spatial and temporal scale of the study, for example whether the focus will be global or within a single catchment, whether it will span one year or multiple years, whether it will include some or all of the value chain, address one product or a facility or an entire company.
Together, the goal and scope indicate which data will be used, how each subsequent step of the assessment will be approached and the level of detail required to achieve the desired results.
Once the goal and scope of the Water Footprint Assessment have been defined, the data are collected to calculate the footprint of the relevant processes for the study.
These may come from global databases, such as WaterStat, or collected locally. The calculations for the green, blue and grey water footprint follow the methodology described in the Water Footprint Assessment Manual.
Water Footprint Assessment is used to assess whether water use is environmentally sustainable, resource efficient and equitably allocated.
In the sustainability assessment step, we are assessing whether water use is balancing the needs of people and nature, if our limited water resources are being used to the greatest benefit and how fairly we are sharing the waters we use.
Environmental sustainability: To be environmentally sustainable, water use must not exceed the maximum sustainable limits of a freshwater resource. We use blue water scarcity to measure the environmental sustainability of the blue water footprint. It’s a measure of the blue water footprint compared to the water available after considering environmental flow requirements. When the blue water footprint is larger than the available water, environmental flows are not met and over time, freshwater ecosystems degrade.
When we consider the environmental sustainability of water use from the perspective of water quality, we compare the grey water footprint with the available assimilation capacity to measure the water pollution level. If the grey water footprint exceeds the assimilation capacity water quality standards are violated and the quality of the water will not meet socially agreed upon purposes.
Both of these, blue water scarcity and water pollution levels, are assessing the cumulative impact of all water uses of the freshwater resource. This can be done for sub-catchment or a local aquifer all the way up to large river basins and regional groundwater reserves.
Resource efficiency: The water footprint is an ideal measure of resource efficiency because it can be measured per unit of production, for example the cubic metres required to produce a ton of wheat. As the water footprint goes down, this indicates a more efficient use of water in producing the wheat or any other product. If the water footprint exceeds a benchmark of resource efficiency for that activity, this indicates that there is the opportunity for water footprint reduction through a change in practices or technology.
Equitable allocation: Unlike the carbon footprint, there are benefits to having a water footprint – the production of the food we eat, the clothes we wear, the materials used in building our homes, etc., requires there to be a water footprint. In addition to ensuring that the water footprint is environmentally sustainable and resource efficient, it also needs to be fairly shared amongst all people. This can mean that the allocation of the water footprint within a river basin is a fair allocation between different water users and different sectors in a way that benefits greater societal goals. It can also mean that no individual, community or country has a larger water footprint associated with the products and services they consume than others.
Using the information gained in the accounting and sustainability assessment steps of Water Footprint Assessment, response strategies that reduce the water footprint and improve its sustainability can be prioritised for implementation.
Response strategies can range from investing in better metering to enable improved water management, to changes in practices or investments in technology that will reduce the water footprint at any step along the value chain. It may also be important to take action collectively with others to improve the long-term sustainability of water use at the catchment or river basin level. Water stewardship and integrated river basin management engage a range of stakeholders in finding solutions which reduce wasteful water use and implement good water governance.