GRP Sectional Cold Water Storage for Data Centres & CNI
Critical National Infrastructure data centres across the UK supporting telecommunications, finance, healthcare, and government operations cannot tolerate cooling failures. Tricel Water supplies KIWA Reg 4 approved, LPCB-accredited GRP sectional cold water storage tanks for cooling water, fire suppression, and twin-compartment configurations across Tier II, Tier III, and Tier IV data centre facilities throughout the UK.
Key facts at a glance
23%
Water-related failures account for 23% of Tier III/IV data centre outages — making on-site storage essential resilience infrastructure
£300k/hr
Maximum downtime cost for CNI data centre service interruption
48–120h
Tier IV cooling water autonomy requirement — storage must sustain independent operation during mains failure
Twin-compartment
Standard configuration for 24/7 supply continuity — one section maintained while the other remains in service
Weekend
Modular GRP installation typically completed within a single planned maintenance window
LPCB + KIWA
Fire suppression and potable water certifications — both held across the full Tricel product range
01
Resilience infrastructure
Water storage as a pillar of CNI data centre resilience
CNI data centres supporting telecommunications, finance, healthcare, and government operations across the UK cannot tolerate cooling failures. Water-related failures account for 23% of Tier III and Tier IV outages, with downtime costs ranging from £4,000 to £300,000 per hour. As UK water stress increases — the 2022 drought affected commercial users across multiple regions — and climate variability intensifies, on-site water storage has moved from optional resilience measure to essential infrastructure.
Water storage in a data centre context serves three distinct functions: cooling water supply for chiller makeup and evaporative cooling towers; fire suppression reserve maintained separately under BS EN 12845:2015; and potable water for welfare and auxiliary services. Each duty has different sizing, compliance, and operational requirements. A single undivided tank serving multiple duties without clear separation creates both regulatory and operational risk.
GRP sectional tanks are specified for CNI data centre applications because of their 25–30 year service life, zero corrosion maintenance cycle, modular assembly in restricted plant rooms, and twin-compartment availability for 24/7 supply continuity.
The resilience argument
A data centre with high-efficiency cooling but insufficient water storage remains vulnerable to supply interruptions. Storage redundancy is as important as mechanical redundancy. For a facility with £50,000/hour downtime exposure, a single 8-hour outage justifies a water storage investment of £400,000 — before any maintenance, insurance, or regulatory benefit is counted.
02
Water storage duties
Data centre water storage applications
Each water duty in a data centre has distinct sizing, compliance, and operational requirements. Separating these clearly at specification stage avoids regulatory non-compliance, insurance voidance, and operational confusion during incidents.
GRP Tanks
Cooling water storage
The primary storage duty. Cooling typically accounts for 30–40% of total data centre energy use. Stored water supports cooling towers, closed-loop chillers, adiabatic systems, and direct liquid cooling during mains supply interruptions.
- Sized by cooling load (MW), water use rate, and autonomy period
- Tier III: 24–48h autonomy; Tier IV: 48–120h autonomy
- Storage sized for peak demand, not average use
- BMS integration for level monitoring and automated refill
- Separate from fire suppression reserve
GRP Tanks
Fire suppression reserve
Sized separately under BS EN 12845:2015 based on hazard classification, hydraulic demand, and required duration. Data centres typically fall within Light Hazard classification. Minimum tank capacity: 135,000–185,000 litres under LH classification.
- Must be physically separated from cooling and potable storage
- LPCB certification to LPS 1276 Issue 2.0 required for insurer compliance
- Dedicated capacity marked and maintained for sprinkler use only
- Pump duty and standby arrangements specified by fire engineer
- Annual capacity verification under BS EN 12845
GRP Tanks
Twin-compartment systems
A twin-compartment tank provides two independently operable sections. One compartment can be isolated for inspection, cleaning, or maintenance while the other maintains full service — the standard approach to planned maintenance in 24/7 CNI facilities.
- Maintains supply continuity during planned cleaning cycles
- Each compartment sized to sustain critical cooling independently
- Clear isolation valve provision between compartments
- Required for Tier IV 2N redundancy compliance
- Available in all Tricel sectional formats
GRP Tanks
Potable and welfare water
Drinking water, washroom supply, canteen, and staff welfare facilities require Regulation 4(1)(a) approved storage separately from cooling and non-potable system water. Materials must be suitable for potable water contact.
- KIWA Regulation 4(1)(a) approval required
- Separate pipework, labelling, and documentation
- Sized on occupancy and operational hours, not cooling demand
- Legionella risk assessment and written control scheme required
- Turnover managed to avoid stagnation in low-occupancy periods
GRP Tanks
Rainwater harvesting
Supplementary non-potable storage for cooling tower makeup water. UK annual rainfall averages 1,154 mm/year. A 5,000 m² data centre roof in a typical UK location could yield 2,700–3,150 m³/year — offsetting 15–30% of typical cooling water demand.
- Separate storage from potable and fire systems
- Multi-stage filtration and biocide dosing required
- BS 8515:2009 compliance for rainwater harvesting installations
- Automated mains backup for periods of low yield
- Viable 20–30% consumption offset in most UK locations
GRP Tanks
Redundant and N+x configurations
CNI data centres are designed to Uptime Institute Tier standards. Storage redundancy must match the facility’s tier classification. A Tier IV facility requires fully independent, fault-tolerant storage with no single point of failure in the water supply chain.
- Tier III (N+1): single fire reserve; 24–48h cooling storage
- Tier IV (2N or 2N+1): duplicate systems; 48–120h cooling storage
- Multiple tanks with independent feeds and isolation
- N+3 configurations used in hyperscale resilience models
- Maintenance without capacity reduction mandatory for Tier IV
03
Material selection
Why GRP is specified for CNI data centre applications
The selection of GRP for CNI data centre water storage reflects operational requirements specific to mission-critical infrastructure: 25–30 year service life, zero corrosion maintenance, structural loading advantages for rooftop plant rooms, and the modular format required to install large-volume tanks within live data centre buildings.
GRP Tanks
Zero corrosion maintenance in 24/7 mission-critical environments
Data centres cannot interrupt cooling water supply for tank corrosion remediation. GRP has no corrosion maintenance cycle — no coatings to inspect, renew, or repair. Unlike galvanised steel, which requires periodic coating assessment and eventually enters a replacement programme driven by degradation at cut edges and fixing points, a GRP tank’s operational status is not subject to progressive material deterioration over its 25–30 year service life.
GRP Tanks
Weekend deployment in operational facilities
Modular GRP panels pass through standard doorways and are assembled in the final plant room location — on rooftops, in basement service areas, and in internal plant rooms without crane lifts or structural modification. Most installations are completed within a single planned maintenance window. For a Tier IV facility where any shutdown carries cost and contractual risk, the ability to install a 150,000+ litre tank over a weekend is a material operational advantage over concrete or steel alternatives.
GRP Tanks
Structural loading advantage for data centre rooftop plant
Data centres typically have dense rooftop plant — chillers, cooling towers, generators, and UPS systems — that already imposes significant structural load on building frames. GRP weighs 15–25 kg/m³ of installed volume, compared with 2,400 kg/m³ for concrete. On a rooftop or elevated plant room where structural reserve is limited, GRP can eliminate the need for strengthening works that would otherwise delay programme and add cost.
GRP Tanks
Twin-compartment availability for 24/7 supply continuity
Twin-compartment GRP sectional tanks allow one section to be isolated, drained, inspected, and cleaned while the other remains in service and supplying cooling infrastructure. This is the operational model required for Tier IV 2N redundancy and for any CNI facility where planned maintenance must not create a cooling supply interruption. No alternative material offers the same combination of modular configurability and certifiable compliance for this application.
04
Regulatory framework
UK compliance requirements for data centre water storage
UK CNI data centre operators face mandatory compliance obligations across six regulatory instruments. Non-compliance carries penalties ranging from £5,000 fines through to £20,000 fines plus criminal prosecution, and can void fire insurance where sprinkler tank capacity or certification does not meet insurer requirements.
Water Supply (Water Fittings) Regs 1999
Requires backflow prevention, contamination control, and demonstration that materials in contact with potable water are of an appropriate quality. KIWA Regulation 4(1)(a) approval is the accepted compliance route for GRP tanks. Annual backflow inspection required; failure risks supply disconnection.
HSE ACoP L8 / HSG274
Legionella risk assessment and written control scheme required for all stored water systems, including cooling towers where Legionella risk is heightened. Temperature monitoring, tank hygiene, stagnation management, and documented records are mandatory. Non-compliance: £20,000 fine and prosecution.
BS 8558:2015
Code of practice for water-efficient water supply systems in buildings. Governs design, installation, testing, and maintenance of water storage and supply systems. Requires quarterly water quality testing by the facilities manager. Failure: enforcement notice.
BS EN 12845:2015+A1:2019
Fixed firefighting systems — automatic sprinkler systems. Tank capacity determined by hazard class, hydraulic design, and required duration. Dedicated capacity must be marked and maintained for sprinkler use only. Annual fire tank verification by fire engineer required; failure voids insurance.
Building Regulations Approved Document G
Sets standards for water efficiency and storage hygiene in non-domestic buildings in England. Water efficiency audit required every five years by an M&E consultant. Failure: local authority fine.
KIWA Reg 4 / LPCB
Tricel Water tanks carry KIWA Regulation 4(1)(a) approval for all potable water storage applications, and LPCB certification to LPS 1276 Issue 2.0 for fire sprinkler duties — both applicable across the full product range, not to selected configurations only.
Insurance requirement
Insurers routinely require LPCB RedBook-listed sprinkler tanks by name when underwriting CNI data centre facilities. A tank that is not LPCB certified — even if it meets BS EN 12845 structurally — may not satisfy the insurer’s approval pathway and can result in fire insurance being voided in the event of a claim.
05
Capacity calculation
Sizing water storage by data centre tier and cooling type
Correct sizing depends on cooling system type, installed power (MW), required autonomy period, fire suppression reserve, and a climate adaptation buffer. Storage sized only to current calculated need without buffer leaves the facility exposed to climate-driven supply variability.
Worked example — 10 MW Tier IV, evaporative cooling
Cooling load: 4 MW (PUE 0.4 for cooling) · Water use rate: 1.5 L/kWh · Daily consumption: 144 m³/day · Target autonomy: 72 hours · Cooling storage: 432 m³ · Fire suppression reserve: 600 m³ · Total: 1,032 m³. Add 20–30% climate adaptation buffer for sites in water-stressed regions (South East England).
Quick reference sizing by tier
|
Data centre tier
|
Power (MW)
|
Cooling water (m³/day)
|
Fire reserve (m³)
|
Recommended storage 72h (m³)
|
Total (m³)
|
|---|---|---|---|---|---|
|
Tier II
|
1
|
25–40
|
150–250
|
75–120
|
225–370
|
|
Tier III
|
5
|
100–180
|
400–600
|
300–540
|
700–1,140
|
|
Tier IV
|
10
|
180–350
|
600–800
|
540–1,050
|
1,140–1,850
|
|
Tier IV (hyperscale)
|
20
|
350–700
|
800–1,200
|
1,050–2,100
|
1,850–3,300
|
Figures are indicative. Final sizing must be based on actual cooling load, cooling system type (evaporative towers consume more than closed-loop chillers), autonomy period, fire suppression hydraulic calculations, and site-specific factors including mains supply reliability and distance to alternative water sources. A 20–30% capacity buffer above calculated need is recommended for sites in water-stressed regions or where climate adaptation planning is required.
Cooling system water consumption
|
Cooling technology
|
Water use (L/kWh)
|
Storage requirement (10 MW)
|
Key trade-off
|
|---|---|---|---|
|
Air-cooled chillers
|
0
|
0 m³ cooling storage
|
No water dependency; higher energy use
|
|
Closed-loop water chillers
|
0.2–0.5
|
50–150 m³
|
Low consumption; requires cooling towers
|
|
Evaporative cooling towers
|
1.2–1.8
|
400–700 m³
|
High efficiency; high water use
|
|
Hybrid (air + evaporative)
|
0.6–1.0
|
200–350 m³
|
Balanced; complex controls
|
|
Direct liquid cooling
|
0.3–0.7
|
100–250 m³
|
Very efficient; high capital cost
|
Based on 8,760 annual operating hours at 4 MW cooling load.
06
Base configuration options
Selecting the right tank layout for the data centre plant room
Data centre plant rooms — whether rooftop, basement, or internal — impose some of the most demanding access and space constraints in any building type. Every square metre of plant room has a capital and operational cost. Tank configuration must be chosen to fit the physical environment precisely, not to meet an ideal specification that the plant room cannot accommodate.
Externally Flanged Base
EFB
Profile
Base flanges external; tank on raised supports allowing gravity drainage and base inspection
Advantage
Complete drainage for cleaning; full base panel inspection; optimal for Legionella control compliance
Limitation
Requires adequate floor-to-ceiling height for raised steelwork — a constraint on many data centre rooftops
Best suited for: New-build hyperscale facilities with dedicated plant areas; ground-level service yards where headroom is not limited; cooling water tanks where full drainage for inspection is a specification requirement.
Internally Flanged Base
IFB
Profile
Base flanges internal; tank sits directly on flat slab — more compact vertical profile
Advantage
Lower overall height; suited to data centre rooftop plant rooms where structural clearance is limited
Limitation
Does not fully gravity-drain; pump required to empty for cleaning and inspection
Best suited for: Rooftop data centre plant rooms with structural height constraints; enterprise co-location facilities being upgraded within existing building fabric; any installation where raised support steelwork is not feasible.
Totally Internally Flanged
TIF
Profile
All flanges internal; can be installed as close as 25mm from wall on two sides
Advantage
Maximum space efficiency in plant rooms where every square metre has a capital cost
Limitation
L-shaped configurations available for awkward or irregular plant room geometries
Best suited for: Internal data centre plant rooms and server building basements where floor space is at a premium; retrofit installations in existing buildings where external clearance is unavailable; any site where the tank must be positioned adjacent to walls or other plant.
Twin-compartment configuration
Twin-compartment tanks — available in EFB, IFB, and TIF formats — divide the stored volume into two independently operable sections. This is the standard CNI data centre configuration: one section maintained while the other remains in service, with no requirement to interrupt cooling water supply for planned cleaning or inspection. Required for Tier IV 2N redundancy; strongly recommended for all CNI facilities.
07
By facility type
Design considerations by data centre segment
The main risks and specification priorities differ across hyperscale, enterprise, edge, and retrofit data centre projects. These differences should drive the written specification, the redundancy architecture, and the maintenance programme.
Hyperscale and Tier IV CNI facilities
Main risks
- Extreme financial exposure from even brief cooling failure
- Large-volume storage creating Legionella risk if turnover is poor
- Complex multi-duty storage requiring clear physical separation
- Climate-driven mains supply vulnerability in drought conditions
Specification priorities
- 2N or 2N+1 redundancy across all storage systems
- Twin-compartment throughout; no single point of failure
- 20–30% capacity buffer above calculated need
- Full BMS integration with automated level and quality monitoring
Enterprise co-location (Tier III)
Main risks
- Shared infrastructure serving multiple tenants with SLA obligations
- Maintenance windows limited by tenant operational requirements
- Retrofit capacity expansion within existing building constraints
- Cooling tower Legionella risk in aerosol-generating systems
Specification priorities
- N+1 storage redundancy minimum; twin-compartment for continuity
- Cooling tower water treatment programme formally documented
- Sectional installation completable within planned maintenance windows
- Clear duty separation with independent meters per tenant where required
Edge and distributed compute sites
Main risks
- Limited plant room space and reduced headroom
- Remote sites with infrequent maintenance visits
- Lower storage volumes creating faster stagnation risk
- Frost risk in exposed or unheated plant enclosures
Specification priorities
- TIF configuration for constrained plant rooms
- Insulation specified where ambient temperature risk applies
- Remote BMS telemetry for level and quality monitoring
- Simplified maintenance access for infrequent site visits
Retrofit and capacity expansion
Main risks
- Existing building fabric limiting access routes and headroom
- Live facility requiring installation without cooling interruption
- Structural loading from additional storage exceeding existing capacity
- Integration with legacy BMS and pipework systems
Specification priorities
- Sectional GRP panels sized for existing access routes
- Structural engineer assessment before procurement
- Installation programme aligned with planned maintenance windows
- Full BMS integration from commissioning; no manual-only monitoring
08
Implementation
Installation in live data centre environments
Water storage installation in a live CNI data centre must be planned around the facility’s operational schedule, structural constraints, and BMS integration requirements. The eight implementation steps below reflect the sequence required for a compliant, commission-ready installation.
Water risk and resilience assessment
Assess mains supply reliability, historical outages, local water stress indicators, and worst-case climate scenarios before specifying capacity
Structural loading assessment
Structural engineer assessment of rooftop or plant room floor loading before procurement — mandatory for all large-volume installations
BMS integration design
Specify level sensors (ultrasonic or radar), flow meters (electromagnetic), water quality sensors (temperature, pH, conductivity), and leak detection from commissioning
Size to tier requirements
Calculate cooling water demand, autonomy period, and fire reserve under BS EN 12845. Add 10–15% buffer plus 20–30% climate adaptation capacity
Foundation level survey
Foundation levelness tolerance: ±2mm over full footprint. Deviation is the leading cause of premature sectional tank joint failure — survey before, not after, procurement
Programme to maintenance window
Most sectional GRP installations completed within a single weekend planned maintenance window — programme around the facility’s lowest-risk outage slot
Case study - CNI Data Centre, South of England
Process Water Storage Resilience, Global Data Centre Facility
Tricel Water supplied and commissioned six hot-press sectional GRP water storage tanks (3 m × 3 m × 3 m each, 27,000 litres per tank, 162,000 litres total) for a large-scale global data centre facility in the South of England. The system was configured with N+3 redundancy — three operational tanks and three configured as contingency standby assets. Shortly after commissioning, a severe storm caused structural damage to two tanks. Cooling operations remained uninterrupted throughout, with the three standby tanks sustaining full process performance while remedial works were completed.
N+3
Redundancy configuration – cooling uninterrupted when storm damage destroyed two tanks
09
Before you specify
Data centre water storage specification checklist
Use this checklist before finalising the water storage specification for a CNI data centre. Each item affects tank type, capacity, compliance route, or the ongoing operational and audit obligations of the responsible person.
Facility tier confirmed (Tier II/III/IV) and redundancy architecture documented
Daily cooling water consumption calculated (L/kWh × installed kW × operating hours)
Fire suppression reserve calculated per BS EN 12845:2015 and sized separately from cooling storage
Twin-compartment arrangement specified for 24/7 supply continuity during maintenance
KIWA Regulation 4(1)(a) approval confirmed for potable water storage tanks
Structural loading assessment completed by structural engineer for rooftop or elevated installations
Access route confirmed for panel delivery: doorway widths, corridor lengths, lift capacity
Legionella risk assessment integrated into water safety management plan under ACoP L8
Cooling system type identified: closed-loop chiller, evaporative cooling tower, adiabatic, direct liquid, or hybrid
Required autonomy period confirmed: Tier III 24–48h; Tier IV 48–120h
10–15% operational buffer and 20–30% climate adaptation capacity included
LPCB certification to LPS 1276 Issue 2.0 confirmed for fire suppression tanks
BMS integration specified: level sensors, flow meters, water quality monitoring, leak detection
Foundation levelness surveyed (±2mm tolerance over full footprint)
Water treatment regime specified: biocide dosing, pH control (6.5–8.5), filtration, cooling tower treatment
Installation programme aligned with planned maintenance window; cooling continuity confirmed during works
Common questions
Frequently Asked Questions
How much water storage does a CNI data centre need?
Requirements depend on facility tier and cooling system type. Tier III facilities typically require 700–1,140 m³ (24–48h autonomy); Tier IV facilities 1,140–3,300 m³ (48–120h autonomy). These figures include fire suppression reserves calculated under BS EN 12845:2015, which must be held separately from cooling water storage. A 20–30% climate adaptation buffer is recommended for sites in water-stressed regions.
What cooling water storage does a Tier IV data centre require?
A Tier IV (2N or 2N+1 redundancy) facility should target 48–120 hours of cooling water autonomy. For a 10 MW facility using evaporative cooling, this equates to approximately 432 m³ of cooling storage over 72 hours, plus a fire suppression reserve of 600 m³ — a total of approximately 1,032 m³ before any climate adaptation buffer. Cooling water consumption varies significantly by cooling system type; evaporative towers consume 1.2–1.8 L/kWh while closed-loop chillers use 0.2–0.5 L/kWh.
What is a twin-compartment tank and why does a data centre need one?
A twin-compartment tank divides the stored volume into two independently operable sections. One compartment can be taken offline for inspection, cleaning, or maintenance while the other remains in service — maintaining supply continuity without interrupting cooling or fire suppression. For 24/7 CNI data centre operations, twin-compartment configuration is the standard approach to planned maintenance, and is mandatory for Tier IV 2N redundancy compliance.
What certifications are required for data centre fire suppression tanks?
Fire suppression tanks should carry LPCB certification to LPS 1276 Issue 2.0, with the tank listed in the LPCB RedBook. Insurers, loss adjusters, and fire engineers routinely specify RedBook-listed products by name; a tank that meets BS EN 12845 structurally but lacks LPCB certification may not satisfy the insurer’s approval pathway. Tricel Weston Ltd sprinkler tanks carry LPCB certification and are listed accordingly.
Can GRP tanks be installed in an operational data centre without a full shutdown?
Yes. Sectional GRP panels pass through standard doorways and are assembled in the final plant room location. Most installations are completed within a single planned maintenance window — commonly a weekend — without requiring structural alteration, crane lifts, or extended facility downtime. This was demonstrated in the case study on this page, where six large sectional tanks were installed and commissioned in a live data centre environment.
What standards govern water storage compliance in UK data centres?
UK data centres must comply with the Water Supply (Water Fittings) Regulations 1999 (backflow prevention and contamination control), Building Regulations Approved Document G (water efficiency and hygiene), HSE ACoP L8 (Legionella risk assessment and control), BS 8558:2015 (building water supply systems), and BS EN 12845:2015 (fire sprinkler water supplies). KIWA Regulation 4(1)(a) approval is the accepted compliance route for potable water storage; LPCB certification covers fire suppression tanks.
RELATED TECHNICAL GUIDES
GO DEEPER ON THE TOPICS THAT MATTER
Each article and checklist in this series covers a specific aspect of cold water storage in data centres at full technical depth, with compliance references, and worked examples.
Standards & Compliance
The Golden Thread
Regulatory framework, Water Fittings Regulations, BS EN 13280, Kiwa certification, ACOP L8, and Building Safety Act golden thread documentation.
CHECKLIST
Water Resilience Assesment Checklist for Data Centres
Cooling demand analysis, supply reliability, storage sizing, infrastructure review, and compliance verification.
CHECKLIST
Data Centre Water System Specification Checklist
Capacity calculations, tank configuration, materials, hydraulic design, monitoring, and certification requirements.
CHECKLIST
Regulatory Compliance Checklist for Water systems
Water regulations, BS standards, Legionella control, fire compliance, environmental permits, and audit readiness.
CHECKLIST
Data Centre Maintenance & Inspection Checklist
Daily, weekly, and periodic inspections, structural checks, sensor validation, water quality testing, and Legionella monitoring.
Technical Guide
Cold Water Tank Sizing for Multi-Storey Buildings
Demand calculations, CIBSE methodology, worked examples, and two-compartment sizing rationale.
White paper — February, 2026 · 40 pages
Water Storage as a Pillar of Resilience in CNI Data Centres
The complete 40-page technical reference. Free to download.
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We supply and install sectional GRP cold water tanks across the UK — capacity from 1,000
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This guide is provided for general guidance and information purposes only. It does not constitute engineering advice and should not be relied upon as the sole basis for design decisions. © 2026 Tricel Water. All rights reserved.
