Critical Dependency Mapping Across Utilities

Detailed Explanation With Case Laws

1. Introduction

Critical dependency mapping across utilities means identifying and analysing how essential utility systems depend on one another. Modern infrastructure is highly interconnected. Electricity, gas, water, telecommunications, transport and digital services cannot always operate independently.

For example:

Electricity failure → water pumps stop → water supply is affected → hospitals face difficulties.

Similarly:

Telecommunications failure → electricity-control communications are disrupted → grid operations become more difficult.

Therefore, dependency mapping helps regulators and utility companies understand which infrastructure depends on which other infrastructure and what could happen if one system fails.

2. Meaning of Critical Dependency

A critical dependency exists where the continued operation of one essential service depends significantly on another service.

Important examples include:

Electricity → Water

Water-treatment plants and pumping stations require electricity.

Electricity → Telecommunications

Mobile networks, data centres and communication systems require electricity.

Gas → Electricity

Gas-fired power stations may depend on reliable gas supply.

Telecommunications → Electricity

Grid operators depend on communication networks for monitoring and control.

Electricity → Transport

Railways, metro systems and electric-vehicle charging depend increasingly on electricity.

Thus, utilities form a network of dependencies rather than separate systems.

3. Purpose of Dependency Mapping

Dependency mapping helps authorities:

identify critical infrastructure;

understand cascading failures;

plan emergency responses;

prioritise investment;

establish backup arrangements;

improve cybersecurity;

coordinate regulators; and

protect essential public services.

The purpose is not simply to create a map. The objective is to understand consequences and vulnerabilities.

4. Direct and Indirect Dependencies

Direct Dependency

A utility directly requires another service.

Example:

Water pumping station → electricity.

Without electricity, the pumps cannot operate.

Indirect Dependency

A utility depends on another system through an intermediary.

Example:

Hospital → telecommunications → electricity.

The hospital needs telecommunications, while telecommunications infrastructure itself depends on electricity.

Indirect dependencies can make infrastructure failures difficult to predict.

5. Cascading Failure

The major legal and operational concern is cascading failure.

Consider:

Substation failure

↓

Electricity outage

↓

Water-treatment disruption

↓

Hospital supply problems

↓

Public-health consequences

One technical failure can therefore create consequences across several sectors.

Dependency mapping allows authorities to identify these chains before an emergency occurs.

6. UK Critical National Infrastructure Framework

The UK recognises Critical National Infrastructure (CNI) across several sectors, including energy, water, communications, transport, health and finance.

The Government's response to the North Hyde incident has specifically supported work to improve the understanding of dependencies between energy infrastructure and other CNI sectors.

This reflects a move away from viewing infrastructure as isolated sectors.

Instead, the focus is increasingly on system-wide resilience.

7. Electricity Supply Emergency Code

The Electricity Supply Emergency Code (ESEC) provides a practical example of dependency-based protection.

The Code establishes a Protected Sites List for electricity-supply emergencies.

It gives particular importance to infrastructure whose loss could affect:

energy-system security;

human life;

public health;

essential services;

national security; and

critical industrial processes.

This shows that electricity protection is partly determined by what other essential services depend upon electricity.

8. Water-Energy Dependency

The relationship between electricity and water is especially important.

Water utilities require electricity for:

abstraction;

pumping;

treatment;

distribution; and

wastewater processing.

At the same time, electricity generation can depend on water for cooling and other processes.

This creates a water-energy nexus.

A serious failure in one sector can therefore create operational problems in the other.

9. Gas-Electricity Dependency

Gas and electricity systems are also closely connected.

Gas-fired electricity generation depends upon:

gas availability;

pipeline capacity;

pressure;

storage;

transport infrastructure.

A gas-supply disruption can therefore reduce electricity-generation availability.

Conversely, gas infrastructure increasingly relies on electricity for control, compression and communications.

This creates two-way dependency.

10. Telecommunications and Digital Dependency

Modern utilities depend heavily on telecommunications.

Grid operators use communications for:

remote monitoring;

control;

protection systems;

data transmission;

emergency coordination; and

operational decision-making.

Water and gas networks similarly use digital monitoring and control systems.

Therefore:

Cybersecurity failure → communications failure → utility-control disruption.

Dependency mapping must therefore include digital infrastructure, not just physical infrastructure.

11. National Security and Investment Act 2021

The National Security and Investment Act 2021 provides an additional protection mechanism.

It permits government scrutiny of certain transactions involving sensitive sectors where national-security risks may arise.

The regime covers specified activities in sectors including energy.

This is relevant to dependency mapping because ownership and control of one infrastructure system can affect another.

For example, control over an important electricity asset could have consequences for:

water supply;

telecommunications;

transport; and

emergency services.

Therefore, dependency analysis can contribute to wider national-security assessments.

12. Relevant Case Law: SSE Generation v CMA

R (SSE Generation Ltd) v Competition and Markets Authority [2022] EWCA Civ 1472

This Court of Appeal case concerned electricity transmission charging arrangements and the relationship between industry arrangements and statutory duties.

Although it did not directly concern dependency mapping, the case demonstrates an important principle:

technical energy arrangements must operate within their statutory legal framework.

This matters because regulators may need to impose obligations on utilities to provide information, maintain resilience or cooperate during emergencies.

Such obligations require proper legal authority.

13. Relevant Case: National Grid v GEMA

R (National Grid Electricity Transmission plc) v GEMA [2018] EWCA Civ 1344

This case concerned the regulation of electricity transmission.

Its wider significance is that technically complex infrastructure decisions remain subject to statutory requirements and judicial oversight.

For dependency mapping, this means that regulators should establish:

who must collect information;

what information must be provided;

how risks should be assessed; and

what regulatory action may follow.

14. Resilience Obligations

Dependency mapping should lead to practical resilience measures.

Utilities may need:

backup electricity;

alternative communications;

standby generators;

spare equipment;

emergency staff;

alternative suppliers;

disaster-recovery systems; and

tested emergency procedures.

The ESEC also recognises that protected-site designation is not a substitute for individual resilience measures such as standby generation and business-continuity planning.

Therefore:

Mapping → risk assessment → resilience requirement.

15. Information Sharing

Dependency mapping requires cooperation between different organisations.

Relevant participants can include:

electricity network operators;

gas companies;

water companies;

telecommunications operators;

transport authorities;

hospitals;

emergency services;

regulators; and

central government.

However, detailed infrastructure information can be security-sensitive.

Therefore, the legal framework must balance:

information sharing + confidentiality + cybersecurity + national security.

16. Legal Challenges

Several important legal questions arise.

Who Must Share Information?

Legislation or licences may need to impose information-sharing duties.

Who Controls the Map?

A central government body may coordinate information, but individual utilities often possess the most detailed technical knowledge.

Who Pays for Resilience?

Investment may benefit several sectors even though one company bears the cost.

How Is Responsibility Allocated?

A failure may involve several utilities, making legal responsibility difficult to determine.

How Much Information Should Be Public?

Transparency must be balanced against infrastructure-security concerns.

17. Future Importance

Dependency mapping will become increasingly important because of:

electrification of transport;

electric heating;

renewable generation;

battery storage;

smart grids;

artificial intelligence;

cloud computing;

digital control systems; and

climate-related disruption.

As more services become dependent on electricity and digital infrastructure, interdependency risk increases.

18. Conclusion

Critical dependency mapping across utilities is a major part of modern infrastructure-resilience law.

Its purpose is to identify:

which utilities depend on each other → what happens when one fails → which failures can cascade → what protection is required.

The UK Government's work following the North Hyde incident demonstrates the increasing importance of understanding dependencies between energy and other Critical National Infrastructure sectors.

The Electricity Supply Emergency Code also shows how infrastructure can receive special protection where its failure could affect energy security, public health, essential services or national security.

The cases SSE Generation v CMA [2022] EWCA Civ 1472 and National Grid v GEMA [2018] EWCA Civ 1344 illustrate the wider legal principle that technical energy regulation must remain within statutory powers and be subject to appropriate legal accountability.

For PhD-level energy-law analysis, the central point is that utility regulation can no longer be based entirely on individual sectors. Electricity, gas, water, telecommunications and transport operate as interconnected systems. Effective dependency law therefore requires cross-sector mapping, information sharing, resilience duties, emergency planning and coordinated regulatory oversight so that the failure of one utility does not develop into a wider societal crisis.