Blue Water Usage

How much "blue water" does it take to grow or raise this ingredient?

Jemima Snow avatar
Written by Jemima Snow
Updated over a week ago

What is the Blue Water Usage metric?

Blue Water Usage is a measure of the amount of blue water required to grow a given ingredient, adjusted for the degree of blue water scarcity in the location where the ingredient is grown. Blue water appropriation refers to the withdrawal and use of water from freshwater lakes, rivers and aquifers for human activities.

The Blue Water Usage metric has two components:

  1. Blue Water Footprint: a crop-and-location-specific blue water footprint (the amount of blue water that a given crop requires in a given location).

  2. Blue Water Scarcity: a location-specific blue water scarcity assessment (the degree of blue water scarcity in a given location), which provides the geographic sustainability component.

Why focus on blue water?

The Blue Water Usage metric focuses on blue water resources specifically. Blue water resources are generally scarcer and have higher opportunity costs than green water, which makes focusing on blue water more impactful for food companies interested in reducing their water footprint. Blue water is also the component of a product’s water footprint that a company has the most control over. Through water-conscious decisions at the supply chain management, companies can influence their impact and reduce their blue water footprint.

Additionally, scientific research on blue water scarcity is more advanced than green and gray water, providing a more complete and reliable impact measurement.

Why is blue water usage important?

Global freshwater withdrawal has increased nearly sevenfold in the past century, and is expected to continue increasing with a growing population and changing dietary preferences. The depletion of blue water from freshwater lakes, rivers and aquifers has negative social and environmental impacts because that water is no longer available to sustain local ecosystems and human livelihoods. It can also restrict the natural flow of water in those areas, causing erosion and contamination.

How does the Blue Water Usage metric relate to agriculture, product development, and the food system?

The water footprint of a food product is the sum of the water required in all of the processes in producing the product. The water footprint within a geographically delineated area (e.g. a province, nation, catchment area or river basin) is equal to the sum of the water footprints of all processes taking place in that area (Hoekstra et al., 2011).

Agricultural water usage is commonly divided into three categories:

  • Blue water represents water in freshwater lakes, rivers and aquifers

  • Green water represents the portion of rainwater that evaporates or transpires through plants;

  • Gray water represents an estimate of the freshwater pollution due to a product or a process

Most crops need an enormous amount of water to grow. When that's entirely from rainfall (green water), there's almost no negative impact. Nearly three-quarters of the world’s cropland is rainfed, but unfortunately, rainfed crops are especially exposed to drought – which is becoming more of a problem due to climate change in many parts of the world.

In the absence of sufficient rainfall, crops are irrigated with water drawn from blue water resources. Currently, the agricultural sector accounts for about 85% of global blue water consumption (Shiklomanov, 2000).

What are the biggest contributors to high blue water impact?

Products or ingredients produced from crops that have a high blue water footprint and are grown in locations with high blue water scarcity will have the greatest overall blue water impact.

For example, growing almonds, which have a high blue water footprint, in a location such as California, which has high blue water scarcity, will score poorly for blue water impact.

How do we measure Blue Water impact?

Blue Water is calculated as the total liters of on-farm blue water required to produce 1kg of ingredient, accounting for the blue water scarcity in the location where the crop is grown.

Blue Water Impact = Blue Water Usage X Blue Water Scarcity [L/kg]

The Blue Water Usage impact spectrum divides the blue water impact values of the ingredients in HowGood’s database into deciles. If an ingredient has an impact lower than 90% of all ingredients in our database, it will score a 10. If it has an impact lower than only 10% of all ingredients in our database, it will score a 1.

Blue Water Threshold Distribution Values:

Ingredients Along the Blue Water Usage Impact Spectrum

HowGood’s Blue Water Usage vs. Water Usage Metric - what’s the difference?

HowGood’s Water Usage and Blue Water Usage metrics both quantify the amount of water required to produce 1 kilogram of product, and contain a location-based sustainability assessment to determine the availability of water in the area that a crop is grown.

The Water Usage metric takes into account green, gray and blue water sources and assigns a water sensitivity factor based on the location in which the crop is grown. The Blue Water Usage metric has been designed according to the water footprint guidelines prepared by Hoekstra et al. (2011), and includes a local sustainability assessment of blue water scarcity.

Data Sources

Mekonnen, M.M. & Hoekstra, A.Y. (2011) The green, blue and grey water footprint of crops and derived crop products, Hydrology and Earth System Sciences, 15(5): 1577-1600.

Hoekstra, A.Y., Chapagain, A.K., Aldaya, M.M. and Mekonnen, M.M. (2011). The water footprint assessment manual. Earthscan, London: Water footprint network.

Mekonnen, M.M. & Hoekstra, A.Y. (2012) A global assessment of the water footprint of farm animal products, Ecosystems, 15(3): 401–415

Mekonnen, M.M. & Hoekstra, A.Y. (2016) Four billion people facing severe water scarcity, Science Advances, 2(2): e1500323

How does my ingredient portfolio compare to others in the industry when it comes to blue water usage?

To see how the Blue Water Usage metric stacks up against the industry average, you can benchmark your portfolio score and metric averages here.

What is the relationship to the HowGood Impact Score?

The Blue Water Usage metric is one of the eight core metrics that make up the HowGood Impact Score. To learn more about the HowGood Impact Score and how the Blue Water Usage metric influences it, click here.

How do I improve impact as a product developer?

  1. Choose a different source location. Since water usage is highly dependent on geography, changing the location where the source material is grown can have a significant impact on water usage.

  2. Choose a different crop or ingredient. If you are using an ingredient that is water-intensive, one of the simplest ways to improve water usage is to choose a different ingredient that is less so, or reduce the amount of the ingredient significantly.

  3. Change growing practices. On-farm practices can have some effect on water usage, though it is highly dependent on the type of crop. Transitioning to dry-farming for crops like almonds or wine that typically grow well in arid climates can reduce water usage and has the added benefit of reducing input and irrigation costs. Drip irrigation systems and mulching can reduce the water that is lost to evaporation. Contour farming—planting rows of crops along the contour of the land rather than in straight rows—acts as a natural barrier to erosion by creating small ledges for the water to pool in and absorb into the soil.

  4. Source animal-based ingredients with their inputs in mind. Ingredients that need the most water are animal-based ingredients because of inefficient feed conversion ratios—meaning to produce a crop you need to use a certain amount of water, whereas to raise an animal you need water for crops to feed the animals and water for the animals. Ideally, animals can be grass-fed or raised on forage, but if that’s not possible, sourcing feed that is less water-intensive is key.

How can I communicate the Blue Water Usage of my products?

The Blue Water Usage metric is used to assess a product’s water footprint and determine its eligibility for the Water Smart attribute. Products that receive the Water Smart attribute have a total blue water impact that is better than 80% of all products assessed by HowGood.

Click here to read more about the Water Smart attribute.

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