Drain gullies play an important part in the sewage system, The wastewater from in-house will begin its journey first to the gullies and then be diverted to the main Drainage system.
A gully is a pipe that connects wastewater or stormwater outlets to drains. They can also be used to prevent flooding by draining surface water from areas prone to Flooding.
Domestic gullies are outside drainage systems that direct water from your garden, guttering, washing machine, dishwasher, bath, shower and sink into the right drains. They typically have a grating or grid to keep debris out of the drains and some sort of trap that holds enough water back to stop odours from entering your home.