Institutional convergence is one of the most important regulatory requirements of water resources management, and its correct application can lead to water sustainability. This article has tried to evaluate the convergence in water policy between the government and the Islamic Council with the method of comparative content analysis. Therefore, to examine the views and concerns considered by the two main institutions of the government and the parliament, at the time of the approval of several important water laws, including the law on fair distribution of water (1361), the law on the transformation of all provincial water affairs departments into regional water companies of the province (1384), and the assignment law Water wells without exploitation license (2009) have been paid. Examining the description of negotiations for the approval of these laws showed that in the plans proposed by the parliament in the water sector, the focus was on facilitating the extraction of underground water resources. But in the government's proposed bill, it was intended to focus on reducing the government's financial burden, downsizing and densifying the government's duties and powers. In many cases, institutional divergence and government experts' opposition to some laws and comments proposed by the parliament prevented the approval of laws facilitating water harvesting. In cases where there was some policy convergence between the two institutions (such as the law of converting offices into companies), it has not been on the path to achieving sustainability and protection of water resources. As a result, in the absence of a good governance platform, institutional convergence and divergence will not lead to maintaining the balance between water sources and uses, and in both cases, the stability and protection of water resources will be jeopardized.