For the first rain washing down, yes. But as the heavy downpour continues, there should be less traces of contaminants. You can try running a carbon to remove any traces. This is assuming you don't live near industrial areas.RBE17;1320497; said:I was going to use rainwater collected from my down spouts for a pond. After reading quite a bit I decided it against it. The main reason being the possible contaminants from the roof.