DIY Rain Barrel Construction and Installation Kit (w/ Downspout Diverter)
Flexi-Fit Rainwater Downspout Diverter (3"x4")
RainRouter Rain Barrel Diverter - YouTube
Downspout Diverters
Downspout First Flush Water Diverter Kit 3"
Amazon.com : EarthMinded DIY Rain Barrel Diverter Parts for 2x3, 3x4 and Round Downspouts (Diverter, Winter Cover Plate, Hose, Hose Seal for Barrel, Parts to fit 3 and 4 inch Round Downpipe) :