OT Security Architect

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, ICS or 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.

Ready to help secure the future of critical infrastructure? Apply today.

Welcome

Our purpose is big. Our impact is huge. And we know that every single one of us has the power, through our actions, to positively change society and the environment for good. It’s why careers with us have real meaning. Because, if you’re driven and ambitious, we can offer you huge opportunities for personal growth, professional development and constant innovation. Forever evolving. Forever focused on doing the right thing, we empower and encourage everyone to play to their strengths and to help us shape a fair and positive future for all. We believe in Water for Life. If you do too, Dive Right In.

We succeed together

Our customers are at the heart of everything we do, because delivering water for life is our core purpose. To achieve this, we need 24/7 support in place to resolve incidents quickly and efficiently. All our employees understand the importance of out-of-hours incident support – because when problems appear, fixing them is our top priority. That’s why our people join together and support when and however needed to make sure our customers get the service they deserve. Joining the Southern Water family means you’ll become part of our incident support team. During your interview, your manager will speak to you about any incident support rotas that apply to your position.

Need flexibility in your work?

Does this opportunity excite you but you’re not 100% sure if you meet all the requirements for the role? Or are you concerned that ‘normal’ office hours aren’t possible given your personal circumstances? Whilst we can’t accommodate every flexible working request, we’ll try to find a practical solution. So why not engage with us and find out more about this role?