As people know most flat roofs tend to accumulate leafs and other debris. Debris buildup on a flat roof can range everything from airborne dust and dirt, animal feces to chicken bones dropped by seagulls.
A manual clean up of the flat roof should be conducted at least twice a year to mitigate any chances of blocked roofing drains. This could include raking the roof clear of debris and clearing out and vegetation from around the roof drains. Using a leaf blower can also be helpful when clearing a flat roof of debris. Always be cautious not to puncture or damage the membrane when clearing the roof.
Roof drains are supposed to have a cover called a “strainer” that filters out debris from entering your internal plumbing. Below is an example of flat roof drain without a proper strainer.
Strainers come in either metal or plastic and some even have a lid that opens on the top for easy access. A variety of metal strainers can be found at this source called Thaler Metal Products.