In preparation for my participation in a water scarcity risks and footprints conference in San Francisco this week, I’ve been thinking about the data that bring life to corporate water footprints. These footprints typically include a company’s water usage and wastewater discharges throughout a value chain, and allow companies to effectively account for water use and impacts. However, collecting meaningful water-related information is difficult at best, and today there is no clear guidance on what information should be collected, especially when it comes to a company’s supply chain.

I started keeping a list of water-related statistics mainly because I noticed that when it came to people, the numbers were never consistent. Consider these:

• 12 billion gallons can supply 200,000 people for one year.
• 200 million gallons is enough for 614 typical U.S. families.
• 10 billion gallons is enough for 400,000 Americans.
• 1 acre-foot can support two families of four for one year.

How much does a village of less than one thousand people in Mali need? How much does one person working as an agricultural day laborer need? How much will it cost to supply that water? These questions make calculating the amount of water required to make one pint of beer or one cotton T-shirt seem relatively straightforward.

BSR is working with one global agricultural company that is struggling with the questions related to drinking water required for individual workers and surrounding communities. What I found fascinating is that the company’s seemingly thorough initial water footprint analysis—providing detailed metrics including blue water, green water, source of irrigation, and 10-year average rainfall for hundreds of production sites—did not highlight the fact that at many of those sites, the company’s contract laborers did not have sufficient access to clean drinking water.

At many of the sites, the company’s contract growers sub-contract the labor to work the fields, which means the company does not account for the volume of drinking water required for these workers. Moreover, at each production site, this amount pales in comparison to the volume of irrigation water required, a second reason that this number often goes unseen. There are no red flags that will draw attention to this volume of water.

But despite the size, the workers’ water is a component of the company’s water footprint, and without it, the company can’t address a fundamental challenge that could pose a significant risk to its agricultural operations.