Thanks for the replies! It's great that there are people out there that practice rain harvesting for household use. I figure you've got quite an investment in that infrastructure. It must be impressive.
Just some clarifications. I don't have issues with impervious surfaces or stormwater handling. Therefore, my primary goal with this rain garden will be a cost effective way of growing wetland plants (without using potable water). I do have a 270 gal pond liner that was on clearance at Lowes for $100 (regular price $285!!) This will will hold the water in the "pond". Keep in mind this will be filled
with soil, there will be no issues with algae. Aeration is not needed since one of the things that wetland plants are adapted for are growing in soil with low or no oxygen (hydric soils).
One of the plant species I'm looking forward to growing is jewelweed: