Water enters near a rainwater outlet despite an intact open slab.
Use the site evidence to agree a project-specific method with the responsible engineer, concrete producer, manufacturer or specialist applicator.
Water enters near a rainwater outlet despite an intact open slab.
Remove grate and inspect clamping flange, membrane tie-in, blockage and slope into the outlet.
A broken transition between membrane and drain body can bypass the field system.
Rebuild a compatible flange, collar or reinforcement detail and restore free drainage.
Use the system's drain detail; avoid folds, fishmouths and unbonded laps around the outlet.
Photograph the detail before closing; confirm flow and perform the specified water test.
Sealant smeared around a grate is not a substitute for a designed drain connection.
References inform the topic; they do not endorse a specific product for this project.