Principal Mechanical Engineer

Principal Mechanical Engineer – Water & Wastewater

Location: Auckland or Wellington, New Zealand
Company: Mott MacDonald

Shape a better world with us

At Mott MacDonald, we employ brilliant people and trust them to do brilliant things. We are a global, employee-owned consultancy delivering work that improves communities, strengthens resilience and creates long-term value across Aotearoa New Zealand and the wider Asia Pacific region.

Our New Zealand water team is growing, and we are looking for a Principal Mechanical Engineer to help lead the design and delivery of high-quality mechanical engineering solutions for water and wastewater projects. This is an opportunity to bring your technical leadership, client focus and passion for mentoring into a collaborative team working on meaningful infrastructure across New Zealand.

The opportunity

As a Principal Mechanical Engineer, you will play a senior role in our mechanical team, leading design across treatment plants, pump stations, pipelines, process facilities and related water infrastructure. You will support projects from optioneering and concept design through to detailed design, construction support and technical review.

You will work closely with process, civil, electrical, structural, digital and environmental specialists to deliver practical, sustainable and buildable solutions for our clients. You will also help grow the technical capability of our team by mentoring engineers, reviewing design outputs and contributing to a culture of quality, collaboration and continuous improvement.

What you’ll do

• Lead mechanical engineering design and technical delivery for 3water projects.

• Design and review mechanical systems for treatment plants, pump stations, chemical dosing systems, sludge handling, pipework, valves, tanks, mechanical equipment, pumping systems and associated plant infrastructure.

• Develop and review technical specifications, calculations, design reports, equipment schedules, datasheets, drawings and construction documentation.

• Provide technical leadership across project stages, including feasibility, concept, detailed design, procurement, construction support and commissioning.

• Work with multidisciplinary project teams to deliver integrated, practical and high-quality engineering outcomes.

• Engage with clients, contractors, suppliers and stakeholders to understand project needs and support successful delivery.

• Lead technical reviews, quality assurance and design risk management activities.

• Mentor and support junior and intermediate engineers, helping them develop confidence, judgement and technical capability.

• Contribute to innovation, sustainability, digital delivery and continuous improvement across our water projects.

• Support bids, proposals and client conversations where mechanical engineering input is required.

About you

You are an experienced mechanical engineer who enjoys solving complex problems, leading design delivery and helping others succeed. You bring strong judgement, clear communication and a collaborative approach to working with clients and project teams.

You will bring:

• A tertiary qualification in Mechanical Engineering or a related discipline.

• Significant experience in mechanical engineering design, ideally within the water, wastewater, industrial process or infrastructure sectors.

• Strong knowledge of mechanical equipment and systems used in water and wastewater treatment environments.

• Experience with pumps, pipework, valves, chemical dosing, odour control, sludge handling, mechanical plant layout, materials selection and equipment specification.

• Confidence leading technical delivery across concept, detailed design and construction stages.

• Experience reviewing technical work and supporting quality outcomes.

• Strong client-facing, communication and stakeholder management skills.

• A collaborative style and genuine interest in mentoring and developing others.

• Chartered Professional Engineer status, or a clear pathway toward chartership, would be highly regarded.

Why Mott MacDonald?

Here, you will be surrounded by global specialists who want to collaborate, share knowledge and help each other succeed. Whether your ambition is to deepen your technical expertise, broaden your project experience, develop your leadership profile or contribute to work that has a lasting impact, you will have the support and opportunity to shape your story.

As an independent, employee-owned business, we make decisions for the long-term benefit of our people, clients and communities. Our people have a real stake in our success, and we reinvest in the things that help them do brilliant work: innovation, sustainability, learning, development and a culture where everyone feels empowered, supported and valued.

For senior roles, this also means you will have a direct pathway towards ownership from day one.

What we offer

• A supportive, collaborative and values-led culture.

• The opportunity to contribute to meaningful water infrastructure projects across New Zealand and the wider Asia Pacific region.

• Career development through mentoring, technical networks, learning and practical project experience.

• Flexible and agile working options, including part-time options where suitable.

• A competitive benefits package, including enhanced KiwiSaver contributions.

• Discretionary group and personal bonuses for eligible employees.

• The chance to be part of an employee-owned business where your voice matters.

Equality, diversity and inclusion

We are committed to creating an inclusive environment where everyone can bring their full self to work. We value diverse perspectives because they help us make better decisions, deliver stronger outcomes and build a better workplace.

If you need any adjustments during the recruitment process, please let us know. We are happy to discuss how we can support you.

Apply now

If you are a collaborative mechanical engineering leader who wants to work on meaningful water infrastructure, support great people and help shape resilient communities across Aotearoa New Zealand, we would love to hear from you.