Water Tanks

If you're talking IBC's I know nothing but P has considered them and almost discounted them because where we would put them would be in daylight and I believe light makes the water go green.

You could fence it in  to stop the water going green? I believe a bit of green to water the plants wouldn't hurt anyway?

I am actually considering having 2. Wondering if digging a hole for it would be feasible. I could pump the water out. I would like it to water my dahlias. I would get better blooms if I could water once a week.