RAINWATER HARVESTING FROM ROOF TOPS IN URBAN AREAS: QUANTITY, QUALITY AND ENVIRONMENTAL BENEFIT : Case studies in Sweden and Colombia

Sammanfattning: This study has looked at two separate locations, Malmö in Sweden, and Medellin in Colombia, and what the possibilities of rainwater harvesting are in those locations. The paper investigated data gathered by low-cost sensors in Malmö region, as well as sampling and measurements of rainwater collected in Malmö and Medellin, analysed by laboratories in both countries. Important data for the paper are quantity, quality, as well as environmental benefits and the economical perspective of rainwater harvesting. There are several steps that can be taken towards a more sustainable use of the Earth’s resources, and rainwater harvesting is included in the possibilities already at hand. But there is need for further development of monitoring and ways to qualify water for different purposes. It is possible to utilize rainwater for many things, and with that, ease the pressure on the local water supply infrastructure. This study has shown some important parts of that process, and that even low-cost sensors can help in gathering essential data for further evaluation of the usability of the rainwater. By collecting parts of the rainwater, flooding due to extensive downpour can be mitigated to some extent. Moreover, considering the low price of the sensors tested in this study, it is possible to use several low-cost sensors to determine the usability to some extent. Had the measurements rendered in values being too low compared to the laboratory results, the risk would have been greater. The consequence is that usable water could be regarded as not usable since the sensors returned an overall higher value compared to the laboratory results. Furthermore, the research found that the environmental benefit can be substantial. But there are more positive implications when gathering water for usage locally. For example, the water supply can become more distributed and with that, less prone to cause events such as water leaks, polluted water, and extreme events that have rendered an unserviceable infrastructure.