This spring I bought a rain barrel, it was very useful for watering plants. I was surpsrised after setting it up how quickly it filled after a few rainstorms. I wonder about two things - would it be safe to use the water from it for vegetable plants? There is a screen on top (where the gutter is directly above) to keep bugs out. Also - the other night I drained it since it's been below freezing. Can I just keep the faucet open or should I remove it?