Rain heads & Box gutters:
Box guttering is great for diverting water away from the roof and down the down pipe. However, they need to be cleaned just like any other gutter cleaning. Aside from the normal dirt and leaves, they are prone to nesting and therefore blockages. Many box gutters have rain heads. These are boxes on the external walls, that catch the water from the box gutter, then direct it down the down pipe. These rain heads also need regular cleaning.
If the rain head or box gutter is blocked, water can quickly build up and cause flooding.
Here are a few photos to help explain.