I caught a lot of rainfall from Hurricane Irene in my gutters from roof runoff and wondered if it'd be safe for watering orchids. (I moved all of 'em inside Friday and have a big job moving them back outside today. Ugh.) I thought this would be a good idea, but the water looks a bit discolored and I'm concerned about some chemical having leached out of the shingles. Or, could just be gunk from leaves, dirt... What would you do?