Drainage Gullies Ireland Essential to any drainage system, drainage gullies play a pivotal role in averting water pooling and property flooding. In Ireland, they’re mandatory for new builds and renovations, adhering to governmental standards. These gullies collect and divert water, drawn from diverse sources like roofs, gutters, and driveways, into a drainage network. The water then finds its way to the municipal stormwater system, steering clear of your property.