Drains and gullies: flooding

Overflowing road gullies (highway drains)

London Borough of Barnet as Highways Authority has drainage responsibilities for carriageways and footways. This is usually done through maintaining existing road gullies (or constructing new ones if required).

A road gully is the slotted iron grating situated in the carriageway adjacent to the kerb. The purpose of the road gully is to collect storm water runoff when it rains.

Report a blocked gully (drain)

If you see water flowing out of a road gully, it could be that it is blocked. You can report a blocked gully by calling us on 020 8359 3555 (office hours Monday to Thursday 9 am to 5:15 pm, Friday 9 am to 5 pm), Out of office hours call 020 8359 2000 or by sending an email to  or report-it online.

Storm events

Although we accept that some road gullies may be blocked and need our attention, in many cases, specially during storm events, it is found that the public sewers are unable to cope with the amount of water generated by the storm, which means that the water is unable to drain away.

In such instances, it is recommended that you and any neighbours who have been  similarly affected, engage with Thames Water (by calling 0800 316 98000 (24 hour service) advising them of the situation. You should provide them with as much detail as possible, supplying date(s) and details of how you were flooded and ask them to ensure that these incidents are logged onto their “flooding history database” as this will contribute to the possibility of an improvement in the sewer system.  

Additionally, the highway drainage systems (gullies) are not designed to cope with heavy storms, so ‘flooding’ of the highway is expected during a storm event but this will go down over time. We investigate each and every reported flooding.