A wetland roof system and method for treating domestic waste water is disclosed which comprises a container having three sections and a L/W ratio greater than 10, a gravel layer deposited at the bottom of the container at a first thickness, a crushed stone layer deposited directly on top of the gravel layer having a second thickness, a sand layer deposited directly on top of the crushed stone layer having a third thickness, a soil layer deposited directly on top of the sand layer having a fourth thickness, and a plant layer growing from said soil layer at a predetermined density.