The estimation of 21 liters of water per small chocolate bar might be a rough average or an approximation based on the total water usage in the chocolate production chain, including irrigation for cocoa plants, processing the cocoa beans, manufacturing the chocolate, and potentially the water footprint from packaging materials.
Please note that the calculation of water usage can vary depending on the specific chocolate production methods, the origin of cocoa, efficiency in water use by manufacturers, and other variables. Additionally, the exact measurement can be challenging to determine precisely due to differences in production practices across regions and companies.
It’s important to consider that water usage estimations can vary, and the figure provided might be an approximation or an average value rather than an exact measurement for all chocolate bars produced.