A health risk assessment methodology based on modelling with a Monte Carlo simulation was applied to harvested rainwater that could be used for domestic use in southern France. Firstly a pilot roof run-off collection system was installed and trace metals analysis in collected rainwater were developed. Next, a model of exposure was built based only on chronic ingestion of rainwater during domestic activities. For exposure scenarios, three type of population were investigated: infants, children, and adults. A fourth scenario was used to determine an average risk for an entire lifetime. A Monte Carlo simulation was carried out to assess uncertainty propagation. The preponderant trace metals in reused rainwater were zinc, iron, aluminium and copper, with average concentrations equal to 4.40x10(-1) mg.L(-1) 5.43x10(-2) mg.L(-1), 5.27x10(-2) mg.L(-1) and 2.06x10(-2) mg.L(-1), respectively. When maximum concentration values were used in calculations, hazard quotients did not exceed 6.4x10(-2), i.e., about 10% of the risk limit. The highest hazard quotients observed for a person during his or her entire lifespan were found for zinc (6.4x10(-2)) and lead (4.5x10(-2)). These health risk assessment results showed that no risk of non-carcinogenic effects from trace metals could be expected from the harvest and reuse of rainwater for domestic activities.