Complii strengthens water compliance and mechanical capability across the Midlands and North with the acquisition of GMS Services

News / Acquisitions / September 28, 2026
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Petra Smith
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Complii, one of the UK’s leading providers of building safety and regulatory compliance services, has announced the acquisition of GMS Services Limited, a specialist water hygiene, water treatment and mechanical services provider operating across the UK. The acquisition comes as the group continues to grow at pace across its five divisions – Water, Air, Fire, Electrical, and Lifts and Escalators.

Headquartered in Wigan, with an operational base in the Midlands, GMS Services has built a strong reputation for quality, technical expertise and reliable service delivery. The business delivers a comprehensive range of water compliance services nationwide, including Legionella risk assessments, water hygiene monitoring and testing, thermostatic mixing valve (TMV) maintenance, tank inspection and cleaning, and disinfection and chlorination.

A particular strength of GMS is its established in-house mechanical and plumbing capability, enabling the business to support customers from initial risk assessment and identification of compliance issues through to the delivery and completion of associated remedial works. GMS is also Gas Safe registered, adding further technical capability to the range of services available within Complii.

GMS Services works with a well-established customer base spanning housing associations, local authorities, healthcare and education, including several national and multi-site contracts. The addition of its people, technical expertise and directly delivered mechanical capability strengthens Complii’s Water division and extends the group’s presence across the Midlands and the North of England.

Becoming part of Complii will also give GMS Services’ customers access to the wider range of building safety and compliance services available across the group, in line with Complii’s ‘One Complii’ approach to customer engagement and service delivery.

Commenting on the acquisition, Sarah Dixon, CEO at Complii, said: “We’re delighted to welcome GMS Services and its team to Complii. GMS has built a strong reputation for quality, technical expertise and dependable service delivery in water hygiene and Legionella compliance. Its established mechanical capability provides an additional strength, while its presence in the Midlands and the North further strengthens our Water division in two important regions for Complii.

“Water safety is fundamental to protecting the people who live, work, learn and are cared for in the buildings our customers manage. Bringing GMS into Complii means we can support more customers, in more locations, with both specialist water compliance expertise and the capability to deliver practical remedial solutions, connected to the full breadth of compliance services available across Complii.”

Gemma Ollerton, Managing Director at GMS Services, added: “Joining Complii is an exciting next step for GMS Services, our people and our customers. We are proud of the reputation GMS has built for quality, technical expertise and service delivery, and becoming part of a larger group gives us the resources and support to build on those strengths and continue growing.

Our customers will continue to benefit from the water compliance and mechanical expertise they know and rely on from GMS, while also gaining access to a much wider range of building safety and compliance services through Complii. We’re looking forward to working alongside colleagues across Complii and continuing to deliver the high standards our customers expect from us.”

The acquisition of GMS Services marks a further step in Complii’s ‘buy and build’ growth strategy, as the group continues to invest in its people, resources, systems and technology, further strengthening its position as a leading provider of building safety and regulatory compliance services across the UK.

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