The Rain Barrel is a furniture you can build (the Outdoors page).
In-game description
A barrel open to the sky. It fills while it rains (a can's worth about every 40 seconds of steady rain, faster in a storm) and holds 10. Fill your watering can at it (click or F, can in hand). E shows how full it is.SHOWN IN THE BUILD RING
Building it
It costs 6 
Wood, 2 
Stone, 2 Water 1 Earth spirits. Take it down with DISMANTLE to get its cost back (see Building).
