Potato Chips' Water Footprint

By Jeanne Yacoubou, MS

The Vegetarian Resource Group received an email inquiry from a European reader about the amount of water needed to produce one bag of potato chips listed in our Save Our Water the Vegetarian Way brochure: http://www.vrg.org/environment/water_brochure.php.

Water Footprints and Virtual Water

In the brochure, we cited data from page 42 Table 4.2 of a UNESCO-IHE Institute for Water Education document authored by Chapagain and Hoekstra (referred to herein as "Report 16") giving global averages of the virtual water content of selected foods: http://waterfootprint.org/media/downloads/Report16Vol1.pdf

The "water footprint" of an individual, business or nation as described in the Introduction (p. 11) of Report 16 is defined as "the total volume of freshwater that is used to produce the goods and services consumed by the individual, business or nation...consists of two parts: use of domestic water resources and use of water outside the borders of the country....[It] includes both the water withdrawn from surface and groundwater and the use of soil water (in agricultural production)."

"Virtual water" in the Summary to Report 16 (p. 9) is defined as "the volume of water required to produce a commodity or service."

A Potato Industry Employee's Perspective: Water Footprint of Potato Chips

The inquirer told us that he had been in the European potato industry for several years, responsible for approximately 300,000 t (approx. 661.4 million pounds) of potatoes used for chips annually in a few countries. He thought that the value (185 L = 48.9 gal.) given in our brochure's table for water needed to produce one 200 g (7 oz.) bag of potato chips was too low.

He suggested that the water usage involved in producing a bag of potato chips from start to finish is significantly higher and should include the water involved in all of the following steps: potato seed production (fresh seed used every year); fertilizer and pesticide production; water loss from outgrade potatoes not meeting all quality specifications and thereby discarded from production lines (on farms: 10-20% and in the chip plants: 3-5%); storage from October to June where there is an ongoing water need to humidify and regulate temperature and ventilation; potato (and thereby water) losses when in long-term storage due to inadequate conditions (8-50% of crop); transporting, washing and processing potatoes during chip production; producing, processing and transporting vegetable oils including palm oil used in the final product; packaging materials manufacture; and transportation from chip plant to distributors and on to retailers.

He related to us a farming scenario when he was an agricultural manager during a drought year: Can you imagine irrigation equipment working 24/7 on one farm which pumped approximately 5,000 cubic meters (approx. 1.3 million gallons) of water per hour onto fields by 8 pumping stations from two rivers and four wells?

In a follow-up discussion, The VRG learned more about the complexities involved in calculating water footprints for potato chips: The paradox with potatoes is that the water supplied to fields and later in the factory is the same water that is removed: potatoes retain 78-81% of water but potato chips, only 2.5-3%. In other words, from a single one-ton (2,205 lbs.) capacity chip production line, the amount of water which must be removed from potatoes exceeds 2.2 t of steam per hour (4,850 lbs. of steam per hour = 9.7 gallons of water per minute).

What Happens to the Removed Water?

I witnessed the water just going up in the air; you could see plenty of steam above every chip factory. I raised the subject of wasted energy and water many years ago, but there was no intention to change anything as there was no external pressure at all.

Another aspect of potato chip manufacture came to light during our discussion. The potato industry manager stated: "...In chips there is 30-35% fat from the oil the chips were fried in during processing. So if we add all water used in the supply chain for all ingredients including the vegetable oil...such as local sunflower or canola oil and imported palm oil...the water usage will be much higher than calculated by the authors you cite in your brochure."

Although VRG's research in October 2015 showed that palm oil is not listed as an ingredient in the top ten potato chip brands sold in the U.S., palm oil is used in some potato chips sold in Europe. Interested readers may learn more about palm oil production and harvest as well as efforts to find alternatives here: http://www.pri.org/stories/2015-09-19/yes-palm-oil-destructive-scientists-arecreating-compelling-alternatives#sthash.OaaVzYqf.dpuf

Are Chapagain's and Hoekstra's Values Accurate?

We pointed out in our response to the reader that Chapagain and Hoekstra had indicated several sources of error in their report. 1) Use of global averages (Values could be significantly more or less in different areas depending on many factors such as climate variability and agricultural practices.) See Summary and p. 41 Table 4.1 for examples. 2) Excluded water needed for processing (p. 38 of Report 16). 3) Many simplifying assumptions (p. 26 of Report 16) when calculating the water footprint of processed products (e.g., potato chips) derived from primary raw commodities (e.g., potatoes): water needed to produce only one raw commodity used to calculate water footprint for each processed product raw commodity produced domestically using only domestic resources. 4) No mention of water footprints of packaging materials and their processing as well as water needed to run production lines in factories.

Chapagain and Hoekstra have expressed concerns over some of their assumptions and choice of certain data sets while discussing their work's shortcomings (pgs. 70-71 of Report 16). These include: using crop water requirements (not actual water used by crops) as a basis, excluding irrigation losses, focusing only on quantitative use of water resources (disregarding impacts of human activities on water quality such as agricultural pollution due to pesticides and fertilizers).


Despite the limitations and qualifying assumptions to all water footprint calculations discussed above, Chapagain and Hoekstra have produced a vast body of knowledge about water footprints, serving as a basis for future refinement by researchers, just as Chapagain and Hoekstra also continue to develop ways to calculate water footprints more accurately.

Post Script: Net-Zero Chips

Some potato chip companies are redesigning their production methods at pilot sites to achieve a "netzero" snack chip: http://www.foodprocessing.com/articles/2012/pepsi-near-net-zero/

The VRG asked the potato industry manager if European companies are also piloting net-zero technologies, and received this reply:

"In some parts of Europe, companies don't have customers with great environmental awareness and since competition is not a factor, no changes are in process that I know of..."

Post Script: Ugly Vegetables

An innovative way for consumers to conserve water used for food production is to purchase the outgrades (i.e., cosmetically blemished fruits and vegetables that are discarded from production lines).

For more information:

Interested consumers may find out more about ugly grocers near them: http://www.endfoodwaste.org/unitedstates.html

For a more complete version of this article, go to our website at: http://www.vrg.org/environment/potato_chips_water_footprint.htm