Indoor Swimming Pool Prices in London & the South East
An indoor swimming pool is the ultimate expression of private wellness in a London home. Protected from the weather, usable every day of the year, and completely private — an indoor pool transforms how you live in your property and can add significantly to its value when designed and built to a high standard.
Indoor pools are also more complex to build than outdoor equivalents. The pool structure itself is only part of the cost: the building that houses it, the environmental control system that manages temperature and humidity, and the integration with the wider property all need careful engineering. This page explains what indoor pool projects actually cost — by type and specification — so you can plan your project with confidence.
The Swimming Pool Company specialises in indoor pool construction across London and the South East, including basement pools, pool conversions within existing buildings, and outbuilding-based pool rooms. Every project is quoted with full itemised transparency and backed by a 10-year structural guarantee.
Indoor swimming pool price guide — London 2026
Outbuilding pool rooms — from £55,000
The most cost-effective route to an indoor pool in London is a purpose-built outbuilding in the garden — often referred to as a pool room or pool pavilion. Under permitted development rules in England, a garden outbuilding placed at least 5 metres from the main house (in most cases) does not require planning permission.
These buildings typically include the pool, a shower and changing area, and basic mechanical services. The structure itself can range from a timber-frame clad building to a contemporary glass and steel pavilion.
Typical prices for outbuilding pool rooms:
-
Basic 8m × 3.5m liner pool in a modular outbuilding, wall-mounted dehumidifier, manual cover: from £55,000
-
8m × 4m concrete tiled pool in a quality outbuilding, ducted dehumidification, auto slatted cover: from £85,000
-
10m × 4.5m tiled pool in a bespoke pool room, full environmental control, LED lighting, automated filtration: from £110,000
The building cost is separate and depends heavily on the specification and style you choose — timber frame and cladding sits at one end; structural steel and glass at the other.
Indoor pools within the main house — from £75,000
Converting an existing basement, ground-floor space or extension into an indoor pool is one of the most technically demanding builds in residential construction. Waterproofing, drainage, ventilation and humidity control all need to be specified to professional standards — the consequences of getting it wrong are severe.
Typical prices:
-
8m × 3.5m pool in a converted basement, dehumidification, basic filtration: from £75,000
-
10m × 4m tiled pool in a purpose-built extension, full environmental control, auto cover: from £110,000
-
10m × 5m pool with infinity edge, automated controls, LED feature lighting: from £145,000
Basement and underground pools — from £95,000
London basement pools are a specialist discipline. Most projects involve pools beneath existing properties, accessed via staircase from the ground floor — often combined with a gym, spa suite or wellness area. Structural coordination with a specialist structural engineer is essential, and the programme is longer than for equivalent outbuilding projects.
Typical prices:
-
8m × 4m basement pool, structural shell, dehumidification, full M&E: from £95,000
-
10m × 5m basement pool with spa, automated controls, feature lighting: from £160,000
-
Full basement wellness complex (pool, spa, steam, sauna): from £200,000+
All basement pool prices are subject to a structural survey. We work with approved structural engineers and can manage the full coordination on your behalf.
What's included in an indoor pool build price?
-
Structural survey and engineering coordination
-
Pool design and 3D visualisation
-
Reinforced concrete shell (RCC or shotcrete)
-
Multi-layer waterproofing to BS8102 standards
-
Full mosaic or large-format tiling
-
Coping and pool deck
-
Complete filtration and plumbing system
-
Air-source heat pump or gas heating
-
Environmental control system (humidity, air temperature, air quality)
-
Dehumidification (wall-mounted or ducted, to specification)
-
LED underwater and feature lighting
-
Full electrical installation to NICEIC standards
-
Automated pool cover (slatted or roller)
-
Control panel and building management integration
-
Commissioning and full handover documentation
-
10-year structural guarantee
Environmental control — the most important indoor pool decision
The most common and costly error in indoor pool builds is underspecifying the environmental control system. An indoor pool generates enormous quantities of water vapour, and without adequate dehumidification and air movement, that moisture will condense on walls, windows and structural elements — causing mould, rot, and eventually structural damage.
Wall-mounted dehumidifiers
The entry-level solution for smaller outbuilding pools and pool rooms. Effective for spaces up to approximately 60–70 m², quiet, and relatively simple to install. Cost: £7,500–£15,000 installed. Suitable for basic outbuilding pools where the space does not need to be fully air-conditioned.
Ducted dehumidification systems
The preferred solution for larger pool rooms, integrated indoor pools and all basement installations. A packaged air handling unit delivers treated, dehumidified air via ductwork throughout the pool space, with full control of temperature, humidity and fresh air exchange. Cost: £16,000–£36,000 installed depending on capacity. This is the specification we recommend for any indoor pool that will be used regularly.
Full pool hall air conditioning
For pools in fully conditioned buildings — typically prime residential projects in central London — an integrated air conditioning and dehumidification system provides year-round climate control across both the pool hall and adjacent spaces. Cost: £50,000+. Required for basement pools integrated with a wider wellness complex.
Pool covers for indoor pools
An automatic pool cover is not optional for an indoor pool — it is essential. A cover dramatically reduces evaporation (and therefore humidity loading on your dehumidification system), retains heat overnight, and improves safety. The cover pays for itself in reduced heating and dehumidification costs within a few years.
-
Manual thermal cover on roller: £800–£1,500
-
Automatic slatted polycarbonate cover, recessed housing: £8,000–£14,000
-
Automatic cover with concealed cassette housing: £12,000–£20,000
Indoor pool running costs
For a heated 8m × 4m indoor pool used daily in London:
-
Electricity (heat pump, filtration, dehumidification, lighting): £2,500–£5,000 per year
-
Pool chemicals: £400–£700 per year
-
Annual service and maintenance: £400–£800 per year
-
Total: approximately £3,300–£6,500 per year
A quality automatic cover and modern variable-speed pump will reduce this significantly. We include detailed running cost estimates in every indoor pool proposal.
Planning permission for indoor pools
Outbuilding pool rooms under 4 metres in height, placed more than 5 metres from the main house, and not covering more than half the garden area generally fall under permitted development in England. Pools within the main dwelling (basement or extension) may require a planning application depending on whether they involve a change to the building envelope. We advise on your specific situation at the survey stage.
Indoor pools require careful planning. We offer a free initial consultation to discuss your site, your specification and your budget — with no obligation to proceed. Call 0208 058 0871 or send us an enquiry online.