This seems a bit of a daft question but I'll ask it anyway...
We have a few water butts that came with the plot and they don't have lids on (to maximise rain collection I assume). Now the thing is, they're full at the moment but the water has a distinctly green tinge to it, I imagine because it's been sat around for months etc...
My question is, is it safe to use? Or should I be trying to use fresh clean water for my plants?