After the beginning of the rainy season in Ghana and the resulting filling of the natural rainwater retention basins in the pilot regions of Accra, our partner Envaserv started the second measuring campaign. For this purpose, water samples were taken at the end of July from the four permanent water retention areas sampled in the first measuring campaign and analyzed with regard to their water quality. In addition, three more temporary rain retention areas were sampled. The water samples of the second measuring campaign are now being examined with regard to their pollution load and the diluting influence of the rainy season. The results obtained will be compared with the results of the first measuring campaign, which took place between April and May 2020. A last measuring campaign will be carried out in November 2020 at the end of the rainy season.