I have written about this in my report, mainly because of the agricultural subsidies from the British government, including Tesco, Sainsbury, M & amp； Large supermarket chains like S and ASDA directly subsidize dairy farmers, so milk will be cheaper than mineral water. Basically, 90p can buy 2L milk, but 90p can only buy 500ml mineral water. There are some local policies, such as fair trade. In addition, the British financial market system is comprehensive and the futures market is relatively perfect, so dairy farmers don't have to worry about their losses.