This paper extends the sociality of policy learning by means of reviewing its theory and
referring to Latour’s sociology of association, and defines policy learning as the coevolution
of the policy relevant actornetworks and their heterogeneous ideas. The author contends that,
during the process of policy learning, its obstacles arise with the solidification of network
associations and stabilization of knowledge sets into a “consensus.” By contrast, various
imbalances resulting from the actors’ individual learning in different network associations serve
as the necessary foundation for overcoming the obstacles. This paper examines the evolutionary case
of China’s drinking water standards in the past 20 years to verify the mechanisms for the emergence
and surmounting of the obstacles in policy learning from the constructivist perspective. The author
holds that the new national standards are the product of “environment protection” being translated
into an issue of “public safety” by newly participating actors. The marginalization of the
drinking water standards in the two high waves for standardization in the 1970s/1980s and at the
beginning of the 21st century is also reflected upon. Finally, the paper points out possible
hidden difficulties in the execution of the new drinking water standards as resistance exists in
social institutions such as incompleteness in the implementation of the standards and lack of a
thorough comprehension of “public safety.”