Developing countries, such as South Africa, have no choice but to look at innovative and/or alternative approaches, such as public–private partnerships (PPPs), as investment models, to ensure that they eliminate their water infrastructure backlogs. The primary objectives of this research were (a) to develop a PPP framework; (b) to identify PPP investment models for water infrastructure; and (c) to determine key categories, criteria and characteristics for cost-effective PPP investment models to ensure the sustainability of the water infrastructure value chain in South Africa. The framework for PPPs identified five broad categories of investment models for the water infrastructure value chain in South Africa. The research results highlight the aspects of PPPs in addressing (a) water infrastructure needs, (b) an implementation strategy for water infrastructure projects, (c) investment policies and (d) the eradication of water infrastructure backlogs. The total investment estimates in the past 20-year period (1998/1999–2019/2020) have been about US$48.36billion, with the public sector contributing about US$44.32 billion (91.64%) and the private sector only US$4.04 billion (8.36%).Furthermore, the analysis showed that about US$2.75 billion/annum is available based on the current financial arrangements, leaving a financial gap of US$2.83 billion/annum in the water infrastructure value chain.