Is it safe to use the water I collect in my rain barrel for my vegetable garden?
I have asked a few qualified people this question and have gotten conflicting answers. Some say no, because the materials used in roofing tiles are toxic and would transfer to my vegetables. Others say the amount of time the rain is in contact with the roof is minimal, and therefore it is okay. I just put a new rain barrel on the side of my house next to the vegetable bed, and would really like to use it.
As you have seen for yourself, there is not any research available to answer this definitively. It becomes a personal choice based on your level of comfort.
Certainly, if you do decide to use it, we'd recommend you water at the base of the plant, right into the soil, as opposed to the leaves. (We recommend this often anyway for most plants, to reduce the time that the leaves stay wet, which can encourage disease).
If you are not comfortable using it on your edibles, feel free to water your other flowers and landscape plants with it.