Objectives: The objective of the study was to develop a model to calculate the cost of water fluoridation in South Africa. Method: A total of 24 input variables were used to create a computerized model in Excel. The input variables could broadly be categorised as follows: chemical cost, labour cost, maintenance cost, opportunity cost and capital depreciation. The following outputs variables were created and were used to evaluate the cost of water fluoridation: Per capita cost per year (PCC), cost-effectiveness analysis (CEA) and cost-benefit analysis (CEA). These calculations were performed for 17 major metropolitan cities, towns and water boards in South Africa, were initially made in 2006 and repeated in 2010 using 2010 input values. Results: The mean per capita cost of water fluoridation for the total population included in the model is R2.52 and it ranges from R0.86 (Botshabelo) (lowest) to R4.55 (Mbombela) (highest). CEA (cost per person per year to save one DMFT) at a caries reduction of 50%, 30% and 10% for all water providers was R24.43, R40.72 and R122.17 respectively. CEA varies from R10.17 for Botshabelo (50% reduction) to R181.81 for Mbombela (10% reduction). CBA (the cost of implementing the procedure divided by the savings in the cost of treatment) at a caries reduction of 50%, 30% and 10% per year for all water providers was 0.11, 0.18 and 0.54 respectively. CBA ranges from 0.04 for Botshabelo (50% reduction) to 0.80 for Mbombela (10% reduction). The cost of water fluoridation increased by 21.1% during the period 2006 to 2010. Conclusion: The results of the study show that water fluoridation is still a viable option to prevent dental caries in communities in South Africa.