A quantitative estimation of the water footprint of the Mexican diet, corrected for washing and cooking water

Abstract

Water is key to food security since agriculture can require up to 85% of a country’s water. Dietary Water Footprint (WF) calculations have recently been used to assess the impact of diet on water use in contexts of water scarcity. However, diet WF calculations are generally done worldwide for cooked foods using raw food databases, with no consideration of food peeling and the water needed to wash and cook food. The WF of the Mexican diet has not been evaluated. We propose a WF calculation model using correction factors for conversion from cooked to raw and peeled to unpeeled foods, and considering the water necessary to wash and cook food. We calculated the WF of the Mexican diet to validate the model and verify its impact on this diet’s WF. We conducted a search of available dietary WF calculation methodologies, a review of the food components of the Mexican diet, a confirmatory study through 24-h recall and interviews, and an exploratory study of 237 adults following the Water Footprint Network (WFN) method. The WF of the Mexican diet using traditional WFA was 7750 l of water per person per day (l/p/d), and our proposed methodology (which included correction factors and food cooking and washing) increased the WF to 8334 l/p/d, an increase of 584 l/p/d. This is between 148% and 363% higher than WFs reported for other diets around the world, including the US American and vegetarian in Austria. This study represented the first approach of Mexican diet WF calculation and proved that, among diets WF worldwide, the Mexican diet WF is the highest. Also, we found that correction factors can increase or decrease WFs by up to 135%. Although water for cooking and washing food represent small proportions of the Mexican diet’s WF, in the long term these can generate significant impacts on water availability in Mexico, given the large WF of the diet and scarcity of water in much of the country. Effective management of the Mexican diet’s WF will be crucial for continued food security in Mexico.