EPDM (ethylene propylene diene terpolymer) is a popular rubber roofing membrane known for its durability and flexibility, commonly used on flat or low-slope roofs. Ponding water occurs when rainwater collects and remains on the membrane instead of draining properly. This happens because of insufficient roof slope, blocked drains, or settling of the roof deck over time. While EPDM is generally resistant to water damage, prolonged ponding can accelerate membrane wear, promote algae or debris buildup, and increase the risk of leaks. To diagnose ponding issues yourself, inspect the roof after rain to see if water pools in certain areas longer than 48 hours and check whether drains or scuppers are clogged. Avoid walking on the wet membrane when it’s slippery or very hot, and don’t try to patch with adhesives in standing water, as this can lead to further damage.
If you observe persistent ponding, it’s best to call a roofing professional to assess the situation. A roofer can determine if the roof drainage needs to be improved by adding or adjusting drains, increasing slope using tapered insulation, or repairing deck settling. When consulting a contractor, ask specific questions like, “What solutions do you recommend to improve drainage without compromising my EPDM warranty?” and “How will you ensure water ponding won’t void any existing roof warranties or cause premature membrane failure?” Proper diagnosis and repair can prevent costly water damage and extend the life of your EPDM roof, making sure your investment stays protected.