Leak Repairs - Flat Roof with Water Ponding   « « BACK « « This particular roof had leaves clogging both scupper drains and an inadequate drainage slope. Ponding water greatly reduces the life expectancy of a roof. This flat roof is an extreme example of a water ponding problem. This particular roof had leaves clogging both scupper drains and an inadequate drainage slope. Ponding water greatly reduces the life expectancy of a roof.