[Greenbuilding] galvalume roofing

[candtcampbell at juno.com]

Not very long ago on this list there was some discussion that galvalume, or zincalume as it's called in Australia, is the best roof for harvesting rainwater. However, in the US, it seems that all galvalume is coated with acrylic. So I'm wondering what impact that coating has on the water, specifically whether it has any toxicity?

Tim