I loved this step by step article from 2004 from Greg Bickal, I take no credit. It shows how to use a 55 gallon barrel as a filter. In this case, he is using it for a pond. I want to continue to look at good methods to filter out chlorine from my garden water. I do know there are inline-filters available and that may be the quickest solution. But I would also like to combine some rain water catchment and our city water into a single solution for garden at some point.