Visualising flammable risks in drainage systems

We were appointed to develop a tool and methodology to help Anglian Water manage risk in their drainage system network by evaluating the potential for flammable liquids and gases to enter the system.

Key details

Project name

Visualising flammable risks in drainage systems



Anglian Water

Services provided:

- Risk Analysis 



- Flammable Liquids Assessment 

- Modelling 



United Kingdom 


Introduced in 2002, the Dangerous Substances and Explosive Atmospheres Regulations (DSEAR) is designed to prevent or limit the harmful effects of fires, explosions and similar energy-releasing events and corrosion to metals.

Operators must understand and manage their risk profile by identifying areas where an explosive atmosphere may exist and then introduce control measures to reduce those risks.

If an operator’s catchment uses, stores and/or generates highly flammable liquids or gases, there's always a residual risk of such substances entering the network.

UK water companies operate vast networks, and a significant release into the network could be deemed a catastrophic failure. With a network of 9,000 assets, Anglian Water needed a way to effectively manage risk and prioritise their capital investment.




With in-depth knowledge of DSEAR requirements and water industry network modelling expertise, we were appointed to develop a methodology and tool to help Anglian Water understand the risks.

Commonly referred to as FLIDS (Flammable Liquids in Drainage Systems), the methodology needed to consider the risk of ingress of flammables from a third party (e.g. COMAH sites, petrol stations, petrol delivery, pipelines, etc.), which could be any substance (varying flammable/explosibility characteristics), of any volume. 

We split the project into three phases:

  • A pilot study (two catchments): we built the model to represent the risk estimations based on a defined rule set, such as liquid flow, assets, potential ignition sources, and estimated consequences (population at risk).
  • Validation (10 catchments): this stage was used to refine the tool based on the results from the first phase, such as refining the visualisation of the potential consequences.
  • Roll out (remaining catchments): we ran the model to characterise each of the assets and prioritise, based on estimated risk.

Visualisation of the screening methodology is the first of its kind in the water industry (with modelling). The tool has since been used in various initial design decisions relating to new and refurbished/upgraded assets.

It's also being developed to include additional risk data for the ongoing understanding and visualisation of facility risks, for example, blast radius and RFI sources. 

Project statistics

assets assessed
catchments assessed
potential sources of flammable material identified

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