Identifying gully grate blockages to prevent flooding

There are a number of reasons for blockage of drainage gully grates; from material being sluiced in during bad weather in the winter, to heavy rainfall after a dry spell, to persistent long term build up of detritus. Any occasion where the grate of a gully is blocked will mean it’s ability to clear water from roads is affected. Sometimes this blockage will be short-lived, for instance leaves in the autumn, but on other occasions it will lead to preventable flooding.

How can DMS drains help?

DMS revolutionary smart drains help out in a number of ways. In addition to a cycle safe composite surface, level measurement for what is going on under the drain, road temperature and tamper detection, DMS Smart drains also feature grate blockage detection. This will allow you to simply visualise via simple online software or your preferred asset management or GIS solution, which drains are experiencing grate blockage.

How does it work?

DMS Smart drains have sensors that are built into the walls of the grate. These tiny, UV, mould and scratch resistant sensors look for blockages by constantly looking for changes in the drainage area. This works much like the sensor on a supermarket checkout conveyor that identifies when the groceries are piled up ready for the cashier. A second part of this sensor is also able to accurately detect light levels in the drain. It is sensitive enough to tell whether the drain is blocked or if a car is parked on top of the drain.

This data is then broadcast back to our cloud data service that analyses changes across the whole year, accounting for everything from seasonal changes to short and long term blockage of the gully grate.

The system has four regions of interest in each gully grate allowing for accurate detection and importantly preventing alerts where the gully is still performing. Our Machine Learning algorithms look for patterns that indicate the type of blockages that need to be identified. This filters our short term blockage and validates the data should create an alert.

The system in action.

At one London borough a DMS Smart Gully was installed at the bottom of a grassy slope plagued by run off of mud and grass. Below (Fig 1) is a graph showing the data processed by DMS to help keep the street flood free by alerting the client as the drain gully became blocked.


Fig 1: Blockage Detection in Action

  1. Short term gully blockages displayed by the system that quickly cleared. No intervention was required.
  2. Persistent blockage of the gully grate by mud washed down from the grassy slope.
  3. Data presented on customer web portal with optional email, SMS and voice alerting.

Persistent blockage was identified by the sensors and validated by DMS algorithms before the customer was alerted. The blockage was cleared shortly after and the graph above (Fig 1), shows sensor reporting all was ‘back to normal’ and ready to do its job again.

About DMS

DMS is a specialist manufacturer of innovative smart cities equipment with a mission to make the cities cleaner, safer and more sustainable. We commit to providing Remote, Reliable and Relevant sensors and data for our customers. To find out more about DMS and our range of solutions, navigate to the partner pages of LCRIG or head to

Published 12/08/2020