OT Security Architect

Southern Water; Brighton; Hybrid; GBP 70,000 - 110,000; Full time

Job summary

Southern Water is seeking an experienced OT Security Architect to lead the design and governance of secure OT environments across our operations. This role focuses on securing industrial control systems while enabling digital transformation across sites.

Based in Falmer or Durrington with hybrid work (2 days per week), you will define architectures, manage cyber risk, and work with engineering, IT and cyber security teams to embed security-by-design principles in major programmes and projects.

Qualifications

• Design OT security architectures and frameworks.
• Lead OT security risk assessments and IEC/NIST/ISO/NIS2 compliance.
• Define secure integration between OT and IT environments.
• Communicate complex security concepts to stakeholders.

Responsibilities

• Design and maintain OT security architectures, standards and frameworks.
• Develop secure solutions across SCADA, PLC, DCS, HMI, historian, IIoT and edge environments.
• Creating secure network designs incorporating segmentation, firewalls, DMZs and Zero Trust principles.
• Leading OT security risk assessments and ensuring compliance with IEC 62443, NIST 800-82, ISO 27001 and NIS2.
• Supporting IT/OT convergence initiatives and defining secure integration patterns between operational and enterprise environments.
• Providing expert guidance, threat modelling and security design assurance for projects and programmes.
• Supporting cyber incident response planning, resilience testing and recovery strategies.

Skills

OT security

Industrial cyber

Stakeholder influence

Security-by-design

Threat modelling

Risk assessment

SCADA & OT networks

IEC 62443

NIST 800-82

ISO 27001

Tools

OPC-UA

Modbus

PROFINET

Ethernet/IP

BACnet

DNP3

Job description

Closing Date

2026-12-01

Job Title: OT Security Architect

Location: Falmer or Durrington – Hybrid working (2 days a week)

Salary: depending on skills and experience

Join Southern Water and help protect the critical infrastructure that delivers essential services to millions of customers every day.

We’re looking for an experienced OT Security Architect to lead the design and governance of secure Operational Technology (OT) environments across our business. This is a unique opportunity to work at the forefront of cyber security, engineering and digital transformation, safeguarding industrial control systems while enabling innovation across our operational sites.

What will you be doing?

As our OT Security Architect, you’ll play a pivotal role in ensuring the security and resilience of our industrial control systems, SCADA platforms, automation networks and connected operational technologies. Working closely with engineering, IT, cyber security and operational teams, you’ll define secure architectures, manage cyber risk and embed security-by-design principles across major programmes and projects.

Key responsibilities include :

• Designing and maintaining OT security architectures, standards and frameworks.
• Developing secure solutions across SCADA, PLC, DCS, HMI, historian, IIoT and edge environments.
• Creating secure network designs incorporating segmentation, firewalls, DMZs and Zero Trust principles.
• Leading OT security risk assessments and ensuring compliance with standards including IEC 62443, NIST 800-82, ISO 27001 and NIS2.
• Supporting IT/OT convergence initiatives and defining secure integration patterns between operational and enterprise environments.
• Providing expert guidance, threat modelling and security design assurance for projects and programmes.
• Supporting cyber incident response planning, resilience testing and recovery strategies.

What are we looking for?

You’ll bring a strong background in OT or industrial cyber security, combined with the ability to influence stakeholders and drive secure outcomes across complex operational environments.

You’ll ideally have:

• Extensive experience securing OT, IC & industrial automation environments.
• Strong knowledge of SCADA, PLC, DCS, RTU, HMI and historian technologies.
• Experience designing secure OT networks, including zoning, segmentation, firewalls and DMZ architectures.
• Knowledge of industrial protocols such as OPC-UA, Modbus, PROFINET, Ethernet/IP, BACnet and DNP3.
• Strong understanding of OT cyber security frameworks including IEC 62443, NIST 800-82, ISO 27001 and NIS2.
• Experience with vulnerability management, threat detection, monitoring tools and secure remote access solutions.The ability to communicate complex technical concepts to both technical and non-technical audiences.

Desirable

• Professional certifications such as CISSP, GICSP, TOGAF, SABSA or ISA/IEC 62443.
• Experience working in critical national infrastructure, regulated industries or safety‑critical environments.
• Exposure to cloud‑connected OT environments, edge computing or IIoT platforms.

Why Southern Water?

This is an opportunity to make a real impact by protecting systems and services that communities rely on every day. You’ll work on complex and rewarding challenges, influence strategic technology decisions and help shape the future of OT cyber security across Southern Water.