Go to the following link: http://waterfootprint.org/en/resources/interactive-tools/product-gallery/
Using the rotating product water footprint calculator, compile a meal that you might eat (breakfast, lunch, or dinner) and explain the water footprint (total water required to produce the food that you are eating) for each food or drink in the meal, then provide the total water footprint for the entire meal.
Since the site lists water in litres and food in kilograms (kg), you will have to convert your results into gallons (3.5 litres per gallon) and pounds (2.2 pounds per kilogram).
Keep in mind that some of the foods listed are presented in one-serving sizes, such as a glass of milk. But others are not, such as an entire loaf of bread (1kg). So you will have to estimate the portion of some of these foods that you will eat for your meal.
For instance, for your meal you may have bread (some fraction of an entire loaf), butter (some fraction of the entire stick), two eggs, and a glass of orange juice for breakfast. Bread uses 1608 litres of water per kilogram of bread. A loaf of quality bread weighs about two pounds (1kg), so two slices of toast would be about 1/10 of the loaf and 1/10 of the water footprint (160.8 litres of water). You can figure out the other food portions in this way.
Other websites that may be of help in your calculations:
http://theplate.nationalgeographic.com/2014/12/16/eating-water-up-the-water-footprint-of-food/
https://www.unitconverters.net/volume-converter.html
