I've spotted a few IBC's around the industrial estate where I work which I'm eyeing up for water collection for the plot. They appear to contain AdBlue which is a water and urea mix. Before I knock on and ask have they any going spare, can anyone enlighten my even if I thoroughly rinsed them out would they be safe to use on the veg? My reading of wiki is that it should be alright, albeit I can't see how it'd be organic, but even way back in my school days I wasn't much of a chemist! Thanks.