As global climate change problems become increasingly serious, the world urgently needs to take practical measures to deal with this environmental issue. In this sense, China's carbon peaking and carbon neutrality goals endowed an ingenious solution. Various industries in China have actively responded to this policy call, and various enterprises have started to carry out the work of carbon emission reduction, especially in water supply industry. In order to reduce carbon emission, we must first calculate carbon emissions and understand the level of carbon emission. At present, the carbon emissions accounting of water supply industry is mostly carried out on the partial work of some individual units within the enterprise, and there is no accounting case for the whole process of water supply work. This work innovatively proposes a method to calculate the carbon emissions generated in the whole water supply procedure. The carbon emission in the whole water supply procedure originates from the leakage of water supply network and the maintenance of water supply network, and all the carbon emissions involved in these two aspects are calculated. Moreover, the key points of carbon emission reduction are analyzed according to the accounting results, and a potential carbon emission reduction scheme is proposed. The research can provide a reference for the overall carbon emission accounting strategies and the construction of carbon emission reduction plans in the future.