The purpose of this article is to clarify the impact of financial capacity on the sustainable growth of water supply companies in Vietnam. Based on sustainable growth models proposed by scientists Higgin (1977) [21] and Van Horne (1987) [6]. The basis was collected by the group of authors from 68 enterprises in the industry, with 710 observations from 2010–2023. By using quantitative modeling research, multivariate regression. The group of authors has evidence to determine that financial capacity has a strong impact on the sustainable growth rate of water supply companies, waste management and treatment activities, wastewater in Vietnam. These factors include: Total assets of the company, Investment in fixed assets and profitability of the enterprise. Based on the research results, the group of authors has proposed feasible solutions to improve the financial capacity of water supply companies in Vietnam towards sustainable growth.