Frequently Asked Questions
What is a drainage gully used for? A drainage gully collects surface water and directs it into underground drainage systems. It’s commonly installed in yards, roads, driveways, and hardstanding areas to manage rainfall runoff, reduce flooding, and keep surfaces clear.What is the difference between a trapped and untrapped gully? A trapped gully includes a built-in water seal that prevents unpleasant odours from escaping the drain. It’s typically used in combined storm and foul water systems, or where there’s a risk of oil runoff.
An untrapped gully has a straight outlet, is lighter in weight, and is used where odour control isn’t a concern—making it suitable for simpler surface water-only drainage.
What is a headwall and why is it important? A headwall is a pre-cast concrete structure installed at the outlet of a drainage pipe. It helps control water discharge into open watercourses and prevents erosion of embankments. Headwalls improve stability at the outfall point and can include features like gratings, flap valves, and toe pieces for added functionality.
When should I use a headwall in a drainage system? Use a headwall whenever a pipe discharges into a ditch, stream, culvert, or open watercourse. It’s especially important in areas where erosion or ground movement could threaten the stability of the bank. Headwalls also make inspection and maintenance easier by clearly marking pipe exits.
What are gullies made from? Our gullies are available in both HDPE (plastic) and concrete options.
HDPE gullies are lightweight, easy to install, and ideal for most yard and surface water applications.
Concrete gullies are more robust and suited for heavier loads or longer-term installations.
View our concrete gully options
Do gullies prevent odours and blockages? Yes. Trapped gullies are specifically designed to block odours from foul water systems. Many models also feature rodding access and silt traps, which help prevent blockages and reduce the need for maintenance.
How do I maintain or unblock a drainage gully? Routine maintenance involves removing built-up debris from the sump and using rodding access to clear the outlet.
Read our guide on how to clear a blocked gully
Where can I get technical advice or help choosing a product? Our expert team is here to help. We can advise on gully types, headwall sizing, custom features, and more. Contact us online or call 0121 351 3230 to speak with our team.