Temporary rain water collection assembly for use on a roof of a building

A rain water collection system for a blue roof system, the water collection system comprising:

• a tray assembly comprising a container having sidewalls, a bottom wall and an open top that defines an interior region of said container, said interior region having a plurality of upstanding columns projecting upwardly from said bottom wall, a first set of upstanding columns of said plurality of upstanding columns projecting upwardly from said bottom wall to a first elevated position within said interior region so as to promote the free movement of air and water within said interior region while upwardly facing surfaces on each of said first set of upstanding columns provides a set of coplanar first support surfaces spaced said first elevated position above a plane of said bottom wall;
• a water absorbing layer located in said interior region, said water absorbing layer being supported on said first support surfaces so that an upwardly facing surface of said water absorbing layer is exposed to the environment, said spacing of said first support surfaces above the plane of said bottom wall facilitating the provision of a water collecting space between an underside of said water absorbing layer and said bottom wall to facilitate the flow of excess water that exceeds the water absorbing capacity of said water absorbing layer into said water collecting space of said interior region that is between said underside of said water absorbing layer and said bottom wall;
• and
• said plural sidewalls of said container having plural openings therethrough to facilitate the passage of air into and around said plurality of said first set of upstanding columns, said water absorbing layer, and said water collecting space to enhance the evaporation of water from said water absorbing layer and said water collecting space.