Gullies

Gullies are used as a method of collecting surface water to discharge to a drain. Gullies are either untrapped or trapped. A trapped gully holds water to prevent foul air from escaping the drain. They are used when discharging surface water into a foul drain. In some cases grey water (i.e. from ground floor bathrooms, utility rooms and kitchens) is also discharged into a gully from a waste pipe into the the foul drain. If an untrapped gully is used (sometimes necessary due to space restriction), it must be trapped using a UG42 or UG44 before entering the drainage system.

An untrapped gully can also be used if it is taking surface water, from a rainwater pipe or area of paving for example, into a surface water drain.