- Two or more 55 gallon rain barrels
- DIY rain barrel diverter & parts kit
- Power drill
- Female garden hose end or male-to-female hose adaptor
- Install your first rain barrel. If you need a reminder, follow these instructions linked below for how to install a rain barrel. Since you are connecting two or more barrels, ensure you have sufficient, sturdy, and level space. This is important, especially if you want your barrels to act as a single unit, then they must be level.
- Connect barrels at the top so the surplus will flow into the second barrel—Install your first barrel under a downspout. Using the 1.5” hole saw, drill a second hole, either at the same height of the existing hole or about 2” from the top, in the first barrel. Insert the fitting. Position the second barrel adjacent and connect both holes with the hose provided.
- Connect barrels in a series so the barrels act as a single unit—Measure 2” from the bottom on each barrel. Mark with a line. Using the hole saw, drill a hole using the 1.5” hole saw at the line. Insert threaded seal into hole. Attach hose to bottom drain on first barrel. Connect other end of hose to the bottom of second barrel. Viola! As your first barrel fills, the second barrel will fill at the same level.
Article via https://www.theecologycenter.org/how-to-connect-more-than-one-rain-barrel/