Feasibility of independent water producers using modular reverse osmosis in the City of eThekwini, South Africa

Water insecurity poses a significant challenge to sustainable urban development in eThekwini, South Africa, where many communities face prolonged water shortages and unreliable municipal supply. This study evaluates the economic and technical feasibility of implementing Independent Water Producers (IWPs) to deliver 100 000 L of potable water per day using modular reverse osmosis (RO) systems. The methodology employed combined hydrogeological assessment, process design, and economic modelling. Groundwater from boreholes was selected as the primary water source, and hydrogeological data from regional studies and the National Groundwater Archive were used to estimate potential yields and quality. The treatment system was designed for a worst-case feedwater scenario (Class 4 quality), incorporating pre-treatment units (sand, activated carbon, softening, and iron removal) followed by a high-rejection reverse osmosis unit. The process configuration was developed based on standard RO design principles and verified using supplier specifications. Economic feasibility was assessed using discounted cash flow (DCF) and net present value (NPV) analyses, with cost assumptions derived from current quotations, municipal tariffs, and local construction indices. Sensitivity analyses were then performed to evaluate the effects of variations in feedwater quality, capital cost, and land acquisition on project viability. Results indicate that IWPs using modular RO systems are economically feasible, with an NPV of R460 000 and an internal rate of return (IRR) of 10.7% under highly conservative assumptions. Sensitivity analyses reveal that the project’s profitability improves significantly when using better-quality feedwater or when capital costs are reduced through land leasing or pre-existing infrastructure. This study demonstrates that decentralized water supply using modular RO technology can provide a viable and scalable solution for enhancing water security in underserved urban areas. It offers a framework for future implementation of IWPs, supporting resilience, public-private partnerships, and reduced dependence on centralized municipal systems.