The social value of water resources must be considered when reforming water prices, improving water policy, protecting water resources and devising allocation methods. However, current social value theories for water resources are often unsound. The social value of water resources is defined here based on social system theory. Energy flow within a combined social–ecological system is analyzed, and an emergy analysis method for ecological economics is introduced for unified quantification and to improve the accounting method of the social value of water resources. Taking Zhengzhou in east-central China as an example, the social value of water resources is calculated for 2015. The water resources' total social emergy was 6.04 × 1021 solar equivalent joules (sej) and the unit value was 6.58 × 1012 sej/m3. This corresponds to 3.88$/m3, indicating that the social value of water resources is enormous. This paper proposes that the social value of water is an important component of its ecological economic value, and its social value should therefore be considered by water policy makers. Research of this type can be effective in helping to protect water resources and encourage efficient water use.