Principal Mechanical Engineer

Principal Mechanical Engineer – Water

Leading Engineering Consultancy | Water Sector | Hybrid Working | Long-term Contract | Outside IR35 | Competitive Rate

The Opportunity

We're recruiting a Principal Mechanical Engineer to deliver high-quality mechanical engineering design and technical leadership across multiple water sector projects. You'll be responsible for leading mechanical engineering workstreams, ensuring compliance with sector standards, managing design delivery, and mentoring engineering teams.

Contract Details: Outside IR35 | Competitive daily/monthly rate | Hybrid working| Long-term contract

MUST HAVE: Current water sector experience. This is a senior technical role for an SQEP (Suitably Qualified Experienced Person) mechanical engineer with proven, recent expertise in water, wastewater or biosolids treatment. You'll have the capability to lead mechanical engineering on projects or groups of projects, managing design quality, timescales, cost and compliance. You'll work collaboratively across disciplines, liaising with clients and partners to ensure integrated delivery.

What You'll Be Doing

Mechanical Engineering Design & Delivery

Lead mechanical engineering workstreams on water sector projects
Produce and approve mechanical design deliverables including:

Process Flow Diagrams and Plant Layouts
Equipment Specifications and Datasheets
Pumping system calculations
Material requisitions and procurement specifications

Ensure designs are safe, practical, cost-effective and compliant with UK and international standards
Manage design timescales, budgets and resource allocation
Carry out Lead Mechanical Engineer roles on assigned projects or project groups
Technical Compliance & Quality

Ensure full compliance with Company and Client policies, codes and standards
Maintain rigorous Quality Assurance processes and auditable technical records
Prepare and manage technical files in accordance with CDM requirements
Conduct design reviews and approve design deliverables
Ensure all work meets water sector regulatory and client specifications
Stakeholder & Partner Coordination

Liaise effectively with other engineering disciplines (civil, electrical, process, etc.)
Engage with clients and external partners to ensure integrated design delivery
Communicate design decisions and progress to project management
Manage supplier relationships and technical bid assessments
Support value engineering and cost optimisation discussions
Specialist Mechanical Engineering

Deliver mechanical engineering across multiple water treatment applications
Provide expert input on pumping systems, chemical storage, asset condition
Support feasibility studies and option appraisals
Contribute technical knowledge to bid preparation and early contractor involvement projects

About You

Essential Qualifications & Experience

MUST HAVE: Current water sector experience - ongoing, active work in water treatment, wastewater or biosolids treatment design
Degree in mechanical engineering or closely related discipline
Chartered or Incorporated Engineer status with a relevant professional body, or clear evidence of working towards these professional titles
SQEP (Suitably Qualified Experienced Person) - recognised as having specific knowledge and experience in mechanical engineering for water applications
Minimum 12+ years' mechanical engineering experience in water sector, with significant recent (current) work in water treatment
Demonstrated expertise in one or more specialist mechanical engineering fields:

Water treatment
Wastewater treatment
Biosolids or sludge treatment
Pumping systems design and analysis
Chemical storage and dosing systems
Asset condition surveys and reporting

Proficiency in delivering engineering design across multiple work categories and project types
Expert-level knowledge of:

Mechanical design working practices and installation requirements
Equipment specification, sizing and selection
UK legislation, standards and water sector regulations
Pumping system hydraulics and calculations
Process and mechanical integration
Health, Safety and Environmental compliance

Strong leadership capability - proven ability to lead engineering teams and manage project workstreams
Excellent communication skills - confident engaging with clients, partners, internal teams and stakeholders
Quality and compliance focused - meticulous approach to design quality, documentation and regulatory compliance
Highly motivated -takes ownership of design delivery and technical excellence
Desirable

Experience leading mechanical engineering on major water or infrastructure projects
Familiarity with BIM and integrated design management
Experience with asset management and condition-based maintenance
Knowledge of water treatment processes and best practice design
Experience mentoring and developing junior engineers
Track record on early contractor involvement or design-build projects
Fluency with mechanical design software (CAD, analysis tools, etc.)

The Role in Practice

You'll work on a hybrid basis with flexible working arrangements. You'll report to senior engineering leadership and lead mechanical engineering workstreams across multiple water sector projects. You'll work collaboratively with civil, electrical, process and other engineering disciplines, ensuring mechanical designs integrate effectively with the overall project delivery.

This is senior technical work where your mechanical expertise, leadership and SQEP status directly impact project quality and delivery. You'll be responsible for design quality, compliance and stakeholder satisfaction. Your decisions on technical approach, equipment selection and design strategy shape how projects are executed