The MSS Group
Senior Key Account Manager

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The Vacancy
MSS Group, part of the RSK Group have an exciting new opportunity for an ambitious and driven individual to join their team as Senior Key Account Manager based in Cardiff, UK.
The Role:
Own a portfolio of key water hygiene and legionella compliance accounts, grow them, and help a team of Key Account Managers do the same.
MSS Water is growing. We deliver water hygiene, legionella compliance, water treatment and engineering services to clients across the public and private sector - from universities and NHS estates to rail, industrial, policing and local authority frameworks.
Three things make this different from the same role elsewhere:
- You'll have a portfolio worth having. These are substantial, multi-site, technically interesting contracts with clients who take compliance seriously - not a list of small accounts to babysit. You'll be the commercial owner of those relationships.
- You'll have room to sell. This isn't a farming-only role with a token growth target. You'll have a warm portfolio to protect and grow, genuine cross-sell scope across water hygiene & treatment, engineering, training and consultancy, and a bonus scheme that rewards you for delivering it.
- You'll have the backing of RSK. MSS Water is part of RSK Group, one of the largest environmental and engineering services groups in Europe, with over 15,000 people across 200+ businesses. That means resource, credibility on tender, and genuine long-term career options.
What you will be doing:
- Managing and growing a portfolio of key accounts - you'll be the commercial owner of those relationships, not a coordinator
- Hitting a personal sales and growth target across new business and existing account development
- Identifying and converting cross-sell opportunities across our full service range: water hygiene and legionella compliance, water treatment, engineering and plumbing, training, and consultancy
- Mentoring and supporting our Key Account Managers - sharing what works, helping them develop, and lifting the performance of the whole team
- Owning the commercial health of your accounts: pricing, margin, renewals, contract performance
- Working alongside our operations, technical and compliance teams so what we sell is what we deliver
- Chairing our sales meetings and contributing to operational reviews, keeping the commercial and delivery sides properly joined up
- Supporting LCA and client audits on your accounts
What we need from you (And what we will ask you to evidence at interview):
We're being upfront about this because it saves everyone's time. At interview, we'll ask you to talk through all three:
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Only hits
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- A proven sales track record. Numbers, not adjectives. Targets you were set, what you delivered against them, and over what period. If you've grown an account or a region, we want to hear the before and after.
- A portfolio you can evidence. Accounts you currently manage or have managed - their scale, complexity, and what you did with them. We're interested in what you built and retained, not just what you inherited.
- Real legionella knowledge. You'll need a working understanding of ACoP L8, HSG274 and the LCA framework, and enough technical grounding to hold a credible conversation with a Responsible Person or Duty Holder without needing to phone a colleague. This is the one we won't compromise on - our clients are buying compliance, and they can tell within five minutes whether you understand it.
Also important:
- Commercially confident - comfortable negotiating, pricing and holding a margin conversation
- Able to influence at every level, from site facilities teams to estates directors
- Organised enough to run a portfolio properly without being chased
- A full UK driving licence
Helpful but not essential - we'll support you to develop these:
- Experience mentoring or leading other account managers
- P&L or budget ownership
- Formal water hygiene qualifications (City & Guilds, WMSoc, or equivalent)
What you will get in return:
- Basic salary of £40,000 - £50,000 depending on experience
- Performance-related bonus scheme
- £5,000 car allowance
- 31 days annual leave including bank holidays, rising with length of service
- Life assurance at 3x annual salary
- Digital GP service via Smart Health
- Salary sacrifice electric/plug-in hybrid vehicle scheme
- Cycle to work scheme
- Gym and lifestyle discounts
- Access to our network of internal mental health first aiders, plus bereavement counselling
- Genuine progression - MSS Water is growing and RSK Group has 200+ businesses to move within
About Us
Based in Cardiff, Wales, we are a 500-strong company of skilled professionals operating in regulated and frequently hazardous environments, providing industrial and commercial cleaning, waste management, asbestos removal, water treatment and security services, in addition to asbestos consultancy and retrofit work. Working across the public and private sectors, we are known for being highly responsive and focusing on proactive client management, delivering the best outcomes for our clients.


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Our clients are diverse and include large multinational businesses, tier one contractors and public-sector bodies. Joining MSS is an opportunity to expand your technical remit and work at a company that prioritises its workforce, giving them an opportunity to succeed. We value our people and want them to make the right decisions in the course of their work and succeed with us.
The MSS Group is part of the RSK Group, a leading integrated environmental, engineering, and technical services business providing dynamic, multidisciplinary services to a wide range of sectors. RSK was founded in 1989 and has grown considerably since then.
At RSK, we operate as a group of businesses that work together seamlessly, aiming for growth through diversification. Our strategy helps us build a strong and resilient business, capable of weathering external challenges, while also providing greater value to our clients and more opportunities for our employees.
Since the beginning, our philosophy has remained the same: employ, develop and reward talented individuals. People are crucial to our company, and we recognise that our success hinges on our colleagues' growth. We're committed to preserving RSK's people-first culture, promoting innovation, and fostering a supportive and caring environment for collaboration. At RSK, we want you to be part of our successes and help you reach your career aspirations. We take pride in offering employees fulfilling and challenging careers by promoting ongoing growth and empowering individuals to excel.
We are committed to fostering an inclusive workplace that welcomes individuals from all backgrounds, experiences, and perspectives. We firmly believe that embracing and celebrating the diversity in our workforce makes us a stronger and more innovative company.
By providing workplace adjustments, we make it easier for people to confidently explore and pursue our career opportunities and recognise that flexibility is key to fostering a dynamic and thriving workplace. Many of our office-based positions benefit from a flexible working arrangement, allowing our team members to achieve a balance between professional and personal commitments.
We actively encourage applications from candidates of all genders, races, ethnicities, ages, neurotypes, religions or beliefs, sexual orientations, and those with disabilities.
If you're passionate about making a difference, join us as we work together to build a brighter, more equitable, and sustainable future for all. Do you have what it takes?
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