The project will see the leisure centre receive an extension and refurbishment of the swimming pools area and changing facilities, a new 400 sq m fitness suite, improved reception and café and an overhaul of the existing gym and leisure facilities.
Outside, the building will be extensively remodelled to complement the surrounding environment. Along with a reconfigured car park, landscaping, bicycle storage and electric vehicle charging points.
The diving structure – which needs to be replaced following an inspection earlier in the year – will also be carried out during this project so that it can continue to create and nurture future Olympians, such as Jack Laugher and Oliver Dingley.
Simultaneously, the existing gas boilers will be replaced with heat pumps, along with the installation of solar panels as well as metering and energy monitoring and control systems.
These energy efficiency measures come following a successful £2.4million bid from the borough council through the government's Department for Business, Energy and Industrial Strategy (BEIS) public sector decarbonisation scheme.
Councillor Stanley Lumley, Harrogate Borough Council's cabinet member for culture, tourism and sport, and chair of the board of directors at Brimhams Active, said: "We have ambitious plans to reduce the proportion of the population that are physically inactive but we can't do this without investing in our facilities.
"This multi-million pound refurbishment project for the Hydro, and the investment in both Knaresborough and Ripon, will provide modern, fit-for-purpose facilities that creates opportunities for local people to move more, live well and feel great."
Mark Tweedie, managing director of Brimhams Active, said: "Through the provision of fantastic modern leisure and wellness facilities and engaging, inclusive services we will be able to help many more people become active, lead healthier lifestyles and therefore live longer, more independent and happier lives.”
"This is a really exciting time for leisure, health and wellbeing in the Harrogate district which is thanks to the bold and brave vision of Harrogate Borough Council and their commitment to unprecedented levels of investment."
The project will be carried out in phases and is anticipated to start next spring. Further details will be announced should planning permission be granted later in the year.
The project will complement the new leisure and wellness centre coming to Knaresborough, which will provide a six-lane 25metre pool, learner pool with flume, sauna and steam room, fitness suite and studio, spin studio, café as well as electric car charging points, bicycle storage and large play area.