Oct 26, 2011

Experts Recommend Inclusion of Rainwater Collection Systems in Urban Planning

University researchers reveal better efficiency of plain, sloping roofs over flat gravel roofs

In a recently released study, researchers from the Autonomous University of Barcelona in Spain revealed that plain, sloping roofs can collect up to 50% more higher quality rainwater than flat roofs with gravel, and suggested that rainwater collection systems be incorporated in urban planning.

“It is important to consider the collection of rainwater when planning and designing cities, as this is an alternative water source with many different uses. It can even be used to save drinking water,” said UAB’s Ramon Farreny, one of the co-authors of the study.

The study’s results show that plain, sloping roofs, such as those made of metal or plastic, make it possible to collect up to 50% more rainwater than flat, rough ones. The information was obtained between 2008 and 2010 using four types of roofs on the UAB campus: three sloping roofs (tiled with metal and polycarbonate sheets) and one flat gravel roof.

Water obtained from the sloping roofs was better in terms of physical and chemical quality compared to water collected from the gravel roof. This was observed in the waters’ conductivity, total organic carbon and carbonates. In the water from gravel roofs, greater depositioning of particles and colonization by plants was also observed.

“The inclusion of criteria related to the slope and roughness of roofs in urban planning may be useful in promoting the harvesting of rainwater as an alternative water source. This could also contribute to preventing flooding and water shortages,” said Farreny.

Others also caution that the costs and environmental impact of rainwater collection systems have yet to be assessed. “Although one material may be efficient in collecting or storing the rainwater, it may also be too expensive or cause contamination,” said Tito Morales-Pinzón, another co-author of the study and researcher at UAB and Technological University of Pereira in Colombia.