RON L here = Seresurplus
While I have Well Water here and do not pratice rainwater collection, In the past, when I did, I followed the simple method! I had 5 Gallon buckets I got off the Work site, Pulled a thin sheet of Cheeze cloth over the top (To Collect the dirt and debris) and set them out in an Open area of my yard! Once there were 3/4 full, I added a few drops of Chroline bleach (Unscented) and capped them bacl off and set them in a cool, dry place! They kept for the years I needed them! Hope this is of some simple help to u?