- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 25 Nov 2019
A gulley is a fitting with a chamber which is designed to collect rainwater, wastewater and groundwater, conveying it to an underground surface-water sewer. Gullies can be used to drain waste water and rainfall from buildings, large paved areas and roadsides, pedestrian areas, parking areas, pavements, roofs and so on.
Usually buried in the ground, the gulley’s configuration typically involves a chamber and a trap (sometimes referred to as a trapped gulley), while its top surface often has a grille over which a waste or rainwater pipe can discharge. Trapped gullies can also be used to take waste water from household sinks and baths. Thus, gullies can collect rainwater from roofs, impervious surfaces and waste water from buildings. When used to drain large areas, they are frequently called yard gullies or road gullies.
The gulley’s top grille is usually designed to prevent leaves, litter and large objects from blocking the system, while the trap – which can be a P-, Q- or S-type – prevents odours from escaping into the environment and can make it difficult for rats to reach the surface. Over time, the level of sediment collecting in a trap can cause blockages which may require manual removal or mechanical suction.
When a trapped gulley features a below-ground inlet coming from another gulley or water source, it is termed a back-inlet gulley. The horizontal inlet is typically located below the top grille but above the level of the water seal. Many gulley types provide the facility to rod the system when a blockage occurs down the line.
 Related articles on Designing Buildings Wiki
- Approved Document H.
- Difference between drains and sewers.
- Drainage stack.
- Grease management.
- Groundwater control in urban areas.
- Highway drainage.
- Public sewer.
- Rain gutter.
- Rainwater downpipe.
- Safe working in drains and sewers.
- Sewer construction.
- Soil vent pipe.
- Waste water.
- Water transfers and interconnections.
Featured articles and news
70 buildings from 70 years of Concrete Quarterly. Book review.
Conserving the iron roof at the Albert Dock.
Delivering an infrastructure revolution.
The admissibility of evidence.
How many can you name? 37 anyone?
CIOB respond to the points-based system.
When is the weather considered 'exceptionally adverse'?
ECA backs call for a rolling programme of rail electrification.
What does 'curtilage' mean and why does it matter?
Our duty to prevent harm and protect each other.
A quality perspective.