Great blog article talking about the water quality of rainwater collected from vegetated roofs versus roofs made from traditional materials (asphalt-fiberglass shingles, Galvalume® metal panels, and concrete tiles). The research on water quality was done in Austin, Texas at Lady Bird Johnson (LBJ) Wildflower Center in Austin, "home to one of the first green roof research plots in the state, testing various commercial green roofing systems and other cool roof technologies over the course of many a hot, Texas summer."
The quick one sentence summary: rainwater collected from vegetated roofs have lower turbidity, nitrates, coliform and heavy metals but higher conductivity, dissolved organic carbon. What does that mean? Some stuff that typically ends up in runoff and stormwater is reduced with vegetated roofs. Yay!
