Principal Mechanical Design Engineer - UK Wide

We are looking to strengthen our engineering team with a Principal Civil Design Engineer based at  a suitable location within the UK, with flexible working available. 

Engineer the Future of Water Infrastructure

At MWH Treatment, we're looking for an experienced Principal Mechanical Design Engineer to provide technical leadership across some of the UK's most critical water and wastewater infrastructure projects.

This is a fantastic opportunity for a proven mechanical engineering professional to take ownership of complex design solutions, influence project delivery strategies, support major bids, and mentor engineering teams. You'll play a key role in delivering safe, innovative and commercially effective mechanical designs that support the UK's essential water infrastructure.

As a recognised technical authority, you'll lead the development and assurance of mechanical engineering designs while driving quality, sustainability and engineering excellence across the business.

The Role

As a Principal Mechanical Design Engineer, you will provide authoritative technical leadership across a range of water and wastewater projects, ensuring designs are safe, compliant, buildable and cost effective.

Working closely with Discipline Leads, Chief Engineers, Project Managers, construction teams, clients and suppliers, you will transform complex engineering challenges into practical, high-quality solutions while maintaining the highest standards of technical governance and quality assurance.

Key responsibilities will include:

• Lead and coordinate the delivery of complex mechanical engineering designs within the water and wastewater sector.
• Provide technical leadership and guidance across multidisciplinary engineering teams.
• Develop innovative, practical and risk-balanced engineering solutions.
• Ensure all designs are safe, sustainable, compliant, buildable and commercially effective.
• Produce, review and approve mechanical design calculations, specifications, reports, drawings and technical documentation.
• Support major project bids and contribute to successful project delivery strategies.
• Act as a technical reviewer and maintain high standards of engineering governance and quality assurance.
• Manage technical delivery from broad project briefs, balancing programme, cost, quality and resource requirements.
• Identify and manage technical risks, ensuring issues are escalated and resolved effectively.
• Liaise with clients, contractors, suppliers and key stakeholders to deliver successful project outcomes.
• Support and mentor engineers, helping to strengthen technical capability across the business.
• Promote a culture of continuous improvement, innovation, safety and customer focus.