Concrete sleeper retaining walls with steel H beams as posts are quite expensive. But I persevered and did it my self but it took me almost a year working at it part time as wells doing other jobs. Rainwater in litres = roof area (m2) x mm of rain. So to fill my tank only about 120mm of rain to do it. I thinking of putting anther tank below the one I have (as the land drops away) to catch overflow. Like shed space you can never have too much fresh water available.
