Gully trap (yard / floor gully)

A gully trap is an outdoor or floor-level drainage fitting with a built-in water seal that collects wastewater — kitchen and bathroom wastes, washing-machine discharge, and yard or balcony floor run-off — and carries it into the underground drain, while the water seal stops sewer gas rising back up through the grating. It's the outdoor cousin of the P-trap: a P-trap protects a single indoor fixture, whereas a gully gathers several waste pipes and floor drainage at one point outside. In a Dubai villa the yard gully is often right where the main drain leaves the building, usually next to a cleanout, which is why a blocked or smelly gully is such a common call. Two things go wrong: the grating clogs with sand, grease and hair so the yard floods, or the water seal dries out — easy in the heat, since the trap water simply evaporates when a gully isn't used for a while — and then drain smells come straight up. The fixes are simple (clear the grating; pour a bucket of water down a little-used gully to refill the seal), but a gully that keeps smelling or backing up usually means a blockage further down the run that Al Ghubaiba's plumbing team can rod or jet from the nearest cleanout.