Should be, but a lot of variables involved. Area it is being collected in: if it is industrial area, rain may pick up contaminants from air as it falls to ground. Also, manner in which it is collected. Easiest way is from a roof or guttering ,but what type material is the roof and/or guttering? Some roofs have copper added to the asphalt to inhibit algae growth, not good for inverts, some fish. As with anything in this hobby, do your research first.