In the case of rainwater harvesting projects, the path way may contribute to the water quality in function of construction materials used. To evaluate the impact of collecting surfaces and pathways on the water quality of the rainwater harvested, physico-chemical and bacteriological analyses were performed along the pathway the rainwater takes from the roof to the infiltration pit. Five rain events have been followed for two different roofs of the national school for civil engineering in the region of Paris. The results show different contamination pathways for heavy metals and aromatic compounds (measure as SUVA) between the glass roof and a sandwich tile roof. The latter is far more pollutant, giving levels of 24 ppb for total lead, 1264 ppb for total zinc and SUVA of 3.8 L*mg-C-1 *m. The analysis of Escherichia showed a slight contamination, increasing from 10 2 to 10 3 cfu *100 ml-1 , but no difference between the two surfaces. In the case of the studied building it's recommended to harvest water only from the glass roof and remain so within the norms for unrestricted reuse.