Burrito on My Plate

The Water Footprint of a Vegan versus a Meat Burrito

Background research by Jeanne Yacoubou, MS


Direct (e.g., cooking and showering) and indirect (growing the food we eat) uses of water taken together are called our volumetric water footprint (herein referred to simply as water footprint). In this report, The Vegetarian Resource Group focuses on water footprints of typical components of burritos.

For crops and animal products, The VRG located water footprint average values presented in several reports by researchers M.M. Mekonnen & A.Y. Hoekstra (herein noted as M&H). http://waterfootprint.org/en/ We converted their values presented in cubic meters per metric ton (m3/metric ton) into gallons per pound (gal/lb.)

M&H divide water footprints into three types: green, blue, and grey. Very simply, green water consists of rainfall. Blue water is surface and groundwater (e.g., river and well water). Grey water refers to polluted water caused by runoff and leaching of nitrogen fertilizer used on the crops whose water footprint is being calculated. M&H include grey water footprints in their total values but all other water footprints calculated from data that The VRG received during its investigation do not include grey water. As a consequence, these other water footprints are underestimates of an actual crop's total water footprint.

Yield/acre data were taken from the latest U.S. Department of Agriculture Summary Reports for crops, vegetables, fruits and livestock. We chose 2015 data to determine top producing states and used 2015 yield/acre data in most calculations. In some instances, extension agents provided us with larger data sets.

For this report, The VRG sought crop water requirements based on crop evapotranspiration (ETcrop). This is a measure of the water actually used by plants, mostly evaporated from leaf surfaces or the soil around the plants and released (i.e., transpired) by plants as vapor for self-cooling. Although most of our values do not strictly correspond to ETcroprequirements, they were considered very good approximations by our sources. M&H based all of their values on ETcrop.

We've listed anecdotal accounts of what we researched during five months in 2016 to give the reader a tiny snapshot of what farming looks like today in America considering foods' water footprints.

Wheat flour tortilla: North Dakota was the leading U.S. wheat producer in 2015. A North Dakota extension agent provided us with a yield/acre value based on nine years across all wheat varieties. Since there is practically no irrigation in North Dakota we calculated average annual rainfall for three different areas of the state during this same time period. From this information we approximated a water footprint for wheat.

Rice: Arkansas is the major producer of rice in the U.S. We received total water (irrigation plus rainfall) data for a ten-year period from a University of Arkansas professor. We located USDA yield/acre data for the same time period. From this we approximated a water footprint for unhusked rice.

Pinto and Black Beans: The USDA Crop Summary 2015 provides data for many different varieties of dry beans, including pinto and black beans. North Dakota has the greatest production of dry beans overall. Pinto is the major bean variety grown there. Michigan is the largest producer of black beans in the U.S. Michigan did not provide any data to us but referred us to North Dakota. M&H list water footprint values for three types of "dry beans." All three have the same water footprints in North Dakota. Likewise in Michigan, all three types have the same (although a different) value. This implies that the water footprints of all varieties of dry beans in a given state are averaged to be the same. Thus, for our burrito which calls for pinto and black beans, we used the value calculated for North Dakota pinto beans and the value for Michigan black beans listed in M&H.

Tomato Salsa: Processing tomatoes — California dominates the production of processing tomatoes used to make tomato paste and other tomato products sold in cans, for example in diced form. We considered diced processing tomatoes as a salsa component for this report. During processing, these tomatoes have their peels removed. For this reason, a California extension agent recommended that we consider the M&H value listed for "peeled tomatoes" as corresponding most closely to what the value for diced tomatoes would be (since the latter value is not given in M&H). The VRG received a water footprint value from a major California tomato processing company for the amount of water needed to transform tomatoes coming from fields into canned diced tomatoes.

Fresh Tomatoes: Florida produced the most fresh market tomatoes in 2015. We used the yield data from the USDA Crop Summary. From extension service documents sent to us by a Florida extension agent we estimated an ETcrop value. We also estimated the amount of wastewater produced during cleaning in the packinghouses based on his information.

Corn Salsa: Sweet corn is different from the field corn raised primarily for livestock feed or for ethanol production in biofuels. Minnesota produces the most sweet corn for processing in the U.S. M&H have listings for "maize, green" and "frozen sweet corn," which are identical in water footprint values. M&H values do not include additional water used in postharvest handling, nor any water used in processing of corn that (1) removes kernels from the ears; and (2) rinses, cooks and packages the corn kernels. There is no recent, readily-available U.S. data on water requirements during sweet corn processing.

Onions: M&H present three different onion classifications in their Appendix. Of the three, "Onions, dried but not further prepared" is the closest to onions used in salsa. For our burrito we are not considering dehydrated onions nor fresh onions such as scallions. USDA uses "storage onions" to refer to dry onions. There is no data readily available for water requirements during onion processing.

Chile Peppers: USDA data for chile peppers include "both fresh and dry product combined," whereas M&H separate fresh from dried chile peppers. M&H lists them as "chilies and peppers, green" where "green" means fresh not dry and excludes green bell peppers. We used a water footprint estimate from a California extension agent, as California is the top U.S. producer.

Guacamole: Avocado is the principal ingredient in guacamole. In the U.S., California dominates in production. Most avocados sold in the US are from other countries due to high demand and a relatively small domestic crop.

Tofu: Tofu is derived from soybeans. In the U.S., Iowa is the largest producer. M&H present many soy products in their table of water footprint values. We compared their value for "soybeans" with that derived from Iowan extension agents. Tofu is listed as "soy curd."

Beef: According to the USDA, Texas is the largest producer of beef cattle. By far the largest portion of water required to raise cattle for beef consists of the water needed to grow the crops used to feed them.

Which Water Footprint Value is the Most Accurate?

We assume an American-made burrito and base our final figures on the top producer state water footprint values for each component given in M&H, plus water for processing/cooking. We list a few foreign water footprints based on country of origin information that we received from several restaurant chains serving burritos. M&H do not provide state values for animal products. So only in the case of beef do we use the M&H U.S. average.

Our Rationale: M&H's water footprints consist of averages, meaning some included sample data may have had much smaller or much larger water footprints. In the case of certain foodstuffs, notably animal products, there are very great differences in water footprints depending on type of food production system (e.g., grazing, mixed or industrial) which go far beyond differences due to climate, soil, etc. that affect non-animal crop water footprints.

A food's water footprint from a single farm is always optimal for determining a food's actual water footprint. Next best would be state values. In a single state there are more uniform growing conditions (although some differences), more so than across many diverse areas in one country (e.g., onions growing in Colorado versus Oregon or dry beans in California versus Minnesota).

A major point brought up by many contributors to this investigation was that the very concept of a global average is "meaningless" and even "silly." The people working with individual producers on a daily basis offered the following factors that directly influence the water footprint of a crop: Climate, weather, terrain, soil, previous crop grown on a farm, tillage practice, irrigation and irrigation technique, fertilizer and pesticide application rates and times. These factors often differ dramatically from region to region in a country or around the world. They are only some of the factors that make it very difficult to give a meaningful national average let alone a global average.

Please note that some of our figures in the infographic on the next page include rounding because of the differences when researching restaurant information between fluid ounces, which measure volume, and ounces, which measure weight. Note that researchers have different approaches and make different assumptions, some of which were discussed above. Thus depending on your methods, figures can vary.

Burrito Restaurants Weigh In

The VRG asked Taco Bell, Chipotle, and Moe's Southwest Grill if certain burrito ingredients are home-grown.

Burrito Component Taco Bell Chipotle Moe's Southwest Grill
Soybeans Not pertinent U.S. U.S.
Dry beans U.S. U.S. U.S.
Avocados Mexico (almost 100%), Chile U.S., Mexico, Chile Mexico
Beef U.S., Canada, Australia, New Zealand U.S., Australia Australia, New Zealand (in 2017, U.S.)

Taco Bell provided some country source information on spices without our asking! M&H list some information on spices but to approximate a spice water footprint considering such small quantities used and that we'd need spice ratios in proprietary blends (which companies do not divulge) we chose not to include them in our report. If you're interested in pursuing spice water footprints or any others begin with Appendices II of M&H's Reports 47 and 48. They are great places to start when looking for country and state/province volumetric water footprint average values of many foods you consume. Look at restaurant websites to see if any water usage information is available. If it's not there ask questions! Doing so will not only raise awareness; it will also encourage companies to acknowledge that the virtual water in their menu items or food products influences consumer buying decisions.

Table 1. Water Footprints of Burrito Components (gallons/pound of product rounded to nearest whole number)

Food (FAO classifications Followed by M&H) M&H 2010 Global Average M&H 2010 USA Average M&H 2010 Leading Producer State Average
Wheat 219 262 ND: 173
Rice (Unhusked) 200 174 AR: 172
Brown Rice, (Husked) 260 226 AR: 224
Dry (Pinto) Beans 605 932 ND: 857
Dry (Black) Beans 605 932 MI: 728
Soybeans 257 199 IA: 195
Tofu (Soy Curd) 302 234 -
Fresh Tomatoes 26 15 FL: 17
Peeled (Processing) Tomatoes 32 19 CA: 19
Sweet Corn 84 64 MN: 67
Avocados 140 145 (Mexico: 133; Chile: 218) CA: 142
Dry Onions 41 19 WA: 19
Chile Peppers 45 30 CA: 28
Boneless Beef Cuts 1,846 1,699 (Australia: 1,818; Canada: 1,678; New Zealand: 1,101) -

See an info graphic titled "Burrito on My Plate: The Water Footprint of a Vegan Versus a Meat Burrito" here: http://www.vrg.org/environment/BurritoOnMyPlate.pdf