maybe I missed your point you are worried about holding water over the winter to use in the late summer??? Why not simply drain the tank for winter and fill it in the spring/summer before it dries up?
FYi I would use a much larger tank 1500/2500 gal new septic tank comes to mind, just pump it dry in the fall, cover. reopen and sanitize it before use. its just a homemade temporary cistern
FYi I would use a much larger tank 1500/2500 gal new septic tank comes to mind, just pump it dry in the fall, cover. reopen and sanitize it before use. its just a homemade temporary cistern