plastic water bottles works for me...

Bottles work pretty well...maybe you can scavenge some two-liter bottles.

When I had to fill a barrel recently, I used overturned nursery pots to use up some of the space.

Even one large pot, up-side-down just like the smaller pots in previous post photo - would take up even more room.

Thank you so much. I have quite a collection now, including a 1 gal. Arizona Tea bottle :-) Now to get down to work.