This article addresses the participation, representation, and strategies of interest groups during the reform of the Water Code in Chile. This reform was presented to Congress by the Executive in 2014 and it was approved in early 2022. Drawing upon neopluralist theory and using various sources of quantitative and qualitative information, we carried out a typification of interest groups which were involved in the discussion and legislative process of the reform bill. The empirical analysis reveals a differentiated competition in terms of resources and organization among different interest groups, without the predominance of the business sector. This finding is confirmed by the heterogeneity observed on representation, the importance gained by organizational thematic specialization, and the combination of various direct and indirect action strategies and repertoires to influence the contents of the reform that was approved.