What is a water footprint and why it matters?

September 2023. the new school year has begun and our small team gathers in Paris. On the agenda for this collective meeting: “what are our projects for the coming year?” One topic quickly stands out, everyone is enthusiastic to work on adding a new footprint into the calculator. While two or three other ideas are briefly mentioned, a consensus is quickly reached: it will be about water.

Many converging motivations

Record heat and water restrictions are becoming common

Once again, the summer of 2023 set records that we would rather not see in the Guinness Book. Météo France ranked it as the fourth hottest summer ever recorded in France. The top three? 2018 and 2022. It is getting hotter year after year. This brings us back to carbon, but also… to water.

In 2023, conflicts over water use emerged in certain towns and a battle over water access is starting to appear.

You want to talk about water and biodiversity

We have received many emails and messages: while many of you visit Nos Gestes Climat to learn about the environmental crisis as a whole, the carbon footprint can feel limiting and even frustrating. You would like to see discussions on other topics where you could take action (or already are), gardening and tree planting, water conservation, rainwater collecting, ethical purchases, upcycling… And so would we!

We want to bring awareness to other planetary boundaries

We are fully aware that we are facing a systemic crisis. This is not just about carbon. Everything is interconnected. And we cannot imagine a more sustainable future without understanding that this is not just a mathematical problem of greenhouse gas emissions. We are dealing with nine planetary boundaries, six of which have already been crossed (and soon a seventh one as well). While carbon is an important boundary (as it is closely linked to many others), it is just one among several. When it comes to freshwater, the time has come to rethink how we manage it sustainably. Addressing other boundaries allows us to shift perspectives.

The carbon model is solid and stable

While the carbon footprint model will never be completely exhaustive, as of September 2023, after several important additions (including private swimming pools, which concern more than 10% of French households), we consider the calculator to be pretty complete. This means that no major footprint elements (several hundreds of kgCO2e) are missing for a significant portion of the population (more than 5%). For example:

• Although significant, emissions from private jets affect too few people to lead to a question in our public simulator (fewer than 100,000 flights in France in 2022).
• Despite its widespread use, postal mail has too small a footprint for us to ask users to count their postcards.

This phase has allowed us to free up mental space for creative thinking.

A meeting that sparked an idea

In September 2023, we met with the association SwimForChange to discuss a potential partnership around the upcoming Olympic Games. They told us about a major sporting event they were preparing to raise awareness about water footprint. They wanted to enhance this event with an online water footprint calculator…

Creating the leading water footprint calculator

The decision was made to explore the topic of water footprint. What could it look like? Would it be a separate calculator or integrated into the carbon footprint calculator? Where would the data come from? What does the water footprint even mean?

A whole new research field opened up before us.

What is a water footprint?

Water footprint represents the hidden water consumption in our daily purchases and activities. It includes the water used to grow the cotton for our t-shirts, feed the corn to the pork we eat, or manufacture the electronics we use**. On average, French people have a water footprint exceeding 5,000 liters per day (yes, per day!). Human activity disrupts the water cycle worldwide and some regions are experiencing increasing water stress.

Consulting experts

To develop expertise on the topic, we scheduled multiple meetings with experts. We reached out to awareness organizations, a leading hydrologist and Water Agencies. We took in a lot of new information.

The topic turned out to be deeper, more complex and more nuanced than we had imagined! This only reinforced our feeling that we were tackling an important issue where education would be an answer.

Choosing a calculation method

Some big decisions had to be made. One of the biggest was choosing the calculation methodology, as water footprint does not benefit from the same scientific consensus as carbon footprint. There are multiple ways to calculate it and depending on the method, results can vary significantly. We aligned with the approach taken by the leading water data providers in France. Our calculations rely on the AWARE method which accounts for the water stress of regions where water is withdrawn.

Data expertise

Speaking of data… Unlike carbon footprint, there is no single go-to data source for water footprint. Fortunately, Agribalyse already includes water footprint data for food, and we were relieved to discover that Ecobalyse has initial data on textiles. This provided a solid foundation. For water, this covers a large portion of the footprint. A few months of development later, the new calculator was added to Nos Gestes Climat!

… And who knows, maybe in a year, another footprint will reveal itself?