Abstract: A modular rainwater collection device for collecting rainwater includes a tank that is substantially box-shaped. The tank has a top, a bottom, a tongue end, a groove end and opposing sides. A female coupler is centrally positioned in the groove end and a male coupler, complimentary to the female coupler, is centrally positioned in the tongue end. A top knockout is positioned in the top proximate to the groove end, and a bottom knockout is positioned in the bottom proximate to the groove end. A screen is reversibly couplable to the top knockout. The tank comprises a plurality of tanks. The plurality of tanks is mutually horizontally couplable and mutually vertically couplable, such that the plurality of tanks forms a wall of tanks. Each of the plurality of tanks is fluidically interconnected.