GRP One Piece Water Tanks for Cold Water Storage
Tricel manufactures GRP one piece water tanks from 45 to 16,000 litres as standard, with bespoke options available. Delivered as a single moulded unit — no joints, no seams, no on-site assembly required. WRAS approved for potable cold water storage; insulated and uninsulated options available. Next day delivery on selected in-stock tanks.
- •Single moulded GRP unit — no internal joints or panel interfaces
- •WRAS approved for potable cold water storage; compliant with BS EN 13280:2001
- •CFC-free PU foam insulation on all sides and lid, encapsulated within the GRP laminate
- •AG and Cat 5 AB air gap options; Category 5 break tanks available
- •Next day delivery available on selected in-stock tanks ordered before noon
GRP One Piece Tank — Key Parameters
Capacity range
45 L – 16,000 L standard
Construction
Single moulded GRP unit
Insulation
CFC-free PU foam, all sides + lid
Approval
WRAS / BS EN 13280:2001
Air gap
AG (Cat 1–4) / AB Cat 5
Max temp (WRAS)
23°C potable / 30°C general
Delivery
Next day on selected stock
What is a GRP one piece water tank?
A GRP one piece water tank is a cold water storage tank manufactured as a single moulded glass reinforced plastic unit. It has no internal joints, seams or panel interfaces, which simplifies cleaning and reduces maintenance requirements compared with sectional or two-part tanks. Tricel manufactures GRP one piece water tanks from 45 to 16,000 litres as standard, with bespoke sizes available. Tanks are manufactured to BS EN 13280:2001 and are available WRAS approved for potable cold water storage with CFC-free PU foam insulation. AG and Category 5 AB air gap options are available. Next day delivery is available on selected in-stock tanks.
Tricel - GRP Tank Manufacturer
Made by the manufacturer. Not a distributor.
Tricel manufactures GRP one piece water tanks at production facilities in Weston-super-Mare and Lanark. Every tank leaves our factory as a complete, tested, moulded unit — not assembled from bought-in components. This means consistent dimensional accuracy, confirmed insulation performance and direct technical support from the people who built the tank.
When your project requires a specific size, an unusual configuration or a confirmed WRAS approval reference, you are speaking with the manufacturer — not a reseller reading a datasheet. Bespoke tanks are available where standard sizes do not meet project requirements.
Smallest standard tank
Largest standard one piece
Potable water approval
Break tank option available
WRAS approved GRP one piece water tanks — suitable for potable cold water storage where the full system specification complies with the Water Supply (Water Fittings) Regulations 1999.
WRAS Approved
GRP one piece tanks for potable cold water storage, compliant with water regulations
BS EN 13280:2001
Manufactured to the British and European standard for GRP cold water storage tanks
CFC-Free PU Insulation
25mm standard insulation on all sides and lid, encapsulated within the GRP laminate
Next Day Delivery
Available on selected in-stock tanks ordered before noon, subject to location
01
Applications
Where GRP One Piece Water Tanks Are Used
GRP one piece tanks are the most common choice for cold water storage where access allows direct delivery and the required capacity falls within the standard range. They are used across domestic, commercial and industrial applications for potable and non-potable storage.
Healthcare & NHS
High-Rise & Multi-Storey
Infrastructure & Utilities
Fire Protection
Data Centres
Industrial & Manufacturing
Education
Agriculture
Food & Beverage
Local Authority & Public
Where access to the installation point is restricted or required capacity exceeds 16,000 litres, a two-part or sectional GRP tank should be considered.
02
Product Range
GRP One Piece Water Tank Range
Tricel’s GRP one piece tank range covers standard insulated and uninsulated tanks, Cat 5 break tanks and bespoke options. The right specification depends on intended use, regulatory requirements, temperature conditions and air gap category.
Most common
Insulated GRP One Piece Tank
Capacity
45 L – 16,000 L
Insulation
25mm CFC-free PU foam
Air gap
AG (Cat 1–4)
Max temp (WRAS)
23°C potable / 30°C general
Approval
WRAS / BS EN 13280:2001
Use
Potable cold water storage
Process & non-potable
Uninsulated GRP One Piece Tank
For process water, non-potable storage and applications where temperature control is not a regulatory requirement. Smooth internal surface; GRP is resistant to corrosion and most chemicals.
Capacity
45 L – 16,000 L
Insulation
None
Air gap
AG (Cat 1–4)
Max temp (WRAS)
30°C (confirm for higher temps)
Approval
BS EN 13280:2001
Use
Process water, non-potable
Backflow protection
Category 5 Break Tank (AB Air Gap)
Air gap type
AB — Cat 5 (Type AB)
Protection
Fluid categories 1–5
Float valve
Raised housing with spillover weir
Insulation
CFC-free PU foam
Approval
WRAS / BS EN 13280:2001
Use
Potable cold water storage
Non-standard requirements
Bespoke One Piece GRP Tanks
Where standard dimensions, connection positions or configurations do not meet project requirements, Tricel can manufacture bespoke one piece GRP tanks. Pre-formed cutouts are provided for standard connections; additional positions confirmed at specification stage.
Dimensions
Project-specific
Connections
Position confirmed at design stage
Colour
Standard grey; other RAL on request
Lead time
Confirm at enquiry stage
Material
GRP
Glass reinforced plastic, single moulded unit
Standard
BS EN 13280
British and European cold water storage standard
Internal surface
Smooth
No joints or seams; bacteria-resistant surface
Insulation
25mm PU
CFC-free; encapsulated in GRP laminate on all sides
03
Category 5 Break Tanks
Category 5 GRP Break Tanks - AG vs AB Air Gap Explained
Air gap type determines the level of backflow protection provided from the mains supply. The Water Supply (Water Fittings) Regulations 1999 require the appropriate fluid category protection to be specified based on the risk level of the downstream system. Confirm the required category with the water supplier or water regulations inspector at design stage.
Fluid Categories 1–4
AG Air Gap - Type AG
A standard one piece GRP tank with an AG air gap provides mains protection from fluid categories 1 to 4. The inlet float valve is fitted within the body of the tank at the standard lid arrangement, with the water outlet separated from the mains inlet by the physical air gap.
- Mains water protection from fluid categories 1, 2, 3 and 4
- Float valve fitted in body; standard lid arrangement
- Required for most domestic and standard commercial applications
- Overflow in body of tank; subject to system design
Fluid Category 5
AB Air Gap - Category 5
A Category 5 break tank has a raised float valve housing fitted on top of the lid, complete with a spillover weir. This creates an AB air gap — the highest level of mains backflow protection. Required where the downstream system presents a fluid category 5 risk to the public supply.
- Mains protection from all fluid categories, including category 5
- Raised float valve housing with spillover weir on the lid
- Required for commercial, industrial and healthcare systems with Cat 5 risk
- Overflow in body of tank in addition to spillover weir
The required fluid category and air gap type must be confirmed with the water supplier or a water regulations inspector before specifying. Selecting an AG air gap where a Cat 5 AB air gap is required is a regulatory non-compliance. Confirm requirements at design stage.
04
Tank Sizes
GRP One Piece Water Tank Sizes
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Capacity (litres)
|
Approx. use case
|
Insulated option
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Cat 5 option
|
Next day stock
|
|---|---|---|---|---|
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45 – 250 L
|
Domestic loft, header, small commercial
|
Yes
|
Confirm
|
Selected Sizes
|
|
300 – 1,000 L
|
Commercial, healthcare, schools, break tanks
|
Yes
|
Yes
|
Selected Sizes
|
|
1,500 – 5,000 L
|
Commercial buildings, industrial, booster systems
|
Yes
|
Yes
|
Subject to Stock
|
|
6,000 – 16,000 L
|
Large commercial, industrial, data centre
|
Yes
|
Yes
|
Confirm Lead Time
|
|
Bespoke
|
Non-standard dimensions; confirm at enquiry
|
Yes
|
Yes
|
Manufacture to order
|
Tricel Water Tank Sizes Guide
Full size tables with dimensions and connection data
External dimensions, connection positions, weight (empty and full) and available configurations for every standard one piece GRP tank in the Tricel range.
05
Installation
Installing a GRP One Piece Water Tank
GRP one piece tanks arrive complete and ready to position. No on-site assembly is required. Installation planning should address access route, base preparation, connection positions, insulation continuity and maintenance access.
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Requirement
|
Guidance
|
Notes
|
|---|---|---|
|
Access route
|
Clear continuous path from delivery vehicle to installation point
|
Doorway width, corridor clearance and floor loading must accommodate the complete tank unit at its delivered dimensions
|
|
Base preparation
|
Flat, level and structurally capable of supporting the full loaded weight
|
Concrete slab or equivalent; base flatness to support tank base without distortion
|
|
Maintenance clearance
|
Sufficient clearance around the tank for inspection, cleaning and hatch access
|
Confirm with Tricel installation guidelines; hatch position determines access requirement
|
|
Insulation continuity
|
External insulation on pipework and connections adjacent to the tank
|
Required to maintain water temperature and comply with water hygiene requirements
|
|
Connection positions
|
Pre-formed cutouts provided at standard positions; bespoke positions confirmed at order
|
GRP can be cut and drilled using standard plumbing tools; pre-formed cutouts preferred
|
|
Float valve sizing
|
Float valve sized to match incoming mains supply diameter
|
25mm incoming mains requires a 1-inch float valve; overflow sized to suit; confirm with Tricel if in doubt
|
|
Internal access
|
Hatch size must support cleaning and inspection as required by water hygiene guidance
|
WRAS-approved close-fitting sealed lid; easily removed for maintenance
|
Access
Delivered as a complete unit
Unlike sectional tanks, a one piece GRP tank arrives pre-built. The full tank must be moved through the access route to its final position. Where door widths or stairwells prevent this, a two-part or sectional tank should be considered.
Base
Flat, level, load-bearing
The installation base must be flat and level. The base does not need to be a specific proprietary system, but it must be structurally capable of supporting the tank’s full loaded weight — including the water, insulation and the tank shell itself.
Connections
Pre-formed cutouts and fittings
Standard connection positions are pre-formed during manufacture. GRP is easily cut and drilled using standard plumbing tools where additional connections are needed. Float valve and overflow sizing should be confirmed to the incoming mains supply specification.
Where access to the installation point prevents the complete tank from being moved into position, Tricel’s two-part tanks or GRP sectional tanks should be considered. Speak to technical sales to assess the appropriate tank type for your project access constraints.
06
Compliance & Water Hygiene
Compliance for GRP One Piece Water Tanks
Compliance for potable cold water storage depends on the complete system specification — not the tank alone. The following regulatory framework applies to systems connected to the public mains supply in the UK.
Regulatory framework - what applies
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Reg/Spec
|
Description
|
|---|---|
|
Water Supply (Water Fittings) Regulations 1999
|
applies to all systems connected to the public mains supply; governs design, installation and maintenance of water fittings including storage tanks
|
|
WRAS approval
|
Tricel GRP one piece tanks are WRAS approved for potable cold water storage; confirm WRAS status at the time of order as approval covers the complete specification
|
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BS EN 13280:2001
|
the British and European standard for cold water storage tanks; sets out requirements for materials, dimensions, performance and testing
|
|
Fluid category and air gap
|
the required fluid category determines the air gap type (AG or AB Cat 5); confirm with the water supplier or water regulations inspector at design stage
|
|
Insulation
|
required for potable cold water storage to maintain water below 20°C, reduce Legionella risk and comply with current water regulations; WRAS tanks rated to 23°C for potable use
|
|
Inspection and cleaning access
|
the sealed lid must allow removal for internal inspection and cleaning; access to float valve and connections required for maintenance
|
|
Legionella risk management
|
cold water storage tanks should be assessed as part of the Legionella risk assessment required under HSE L8 and the ACOP; water turnover, insulation and dead-leg elimination are key factors
|
|
Water turnover
|
adequate throughput should be maintained to reduce stagnation; tank sizing should account for minimum daily demand, not only maximum capacity
|
Compliance depends on the full specification
A WRAS-approved tank used with non-approved fittings, pipework or connections does not constitute a WRAS-compliant system. Compliance with the Water Fittings Regulations is the responsibility of the installer and the system designer.
For potable water systems, the complete specification — including tank, fittings, pipework, insulation, float valve, overflow and maintenance access — should be reviewed against current regulatory requirements before installation.
WRAS approval covers the tank as manufactured by Tricel. Approval does not extend to third-party fittings, pipework or system components unless those components are independently WRAS approved.
Tricel provides WRAS approval documentation and BS EN 13280:2001 compliance references on request. Contact technical sales for documentation required for specification, procurement or inspection purposes.
07
Technical Downloads
GRP One Piece Tank Technical Resources
Technical documents for engineers, specifiers, M&E contractors and facilities managers. Includes WRAS documentation, size tables, installation guidance and compliance references.
One Piece GRP Tank Product Brochure
Full range overview — insulated, uninsulated, Cat 5 and bespoke; capacity range and approvals.
Water Tank Sizes — Full Dimensions
External dimensions, connection positions and weight data for all standard one piece GRP tank sizes.
WRAS Approval Documentation
WRAS approval references for potable cold water storage; required for specification and procurement.
08
Specification Support
Get a GRP One Piece Water Tank Quote
For straightforward standard sizes, order or enquire directly. For bespoke dimensions, Cat 5 configurations, next day delivery confirmation or specific compliance documentation, contact Tricel technical sales with the details below.
Useful information for your enquiry
Required capacity (litres)
Air gap type (AG or Cat 5 AB)
Installation location
Installation location
Required delivery timescale
Bespoke dimensions needed?
Insulated or uninsulated
Potable or non-potable use
Access route dimensions
Delivery location and postcode
WRAS documentation required?
Float valve size (mains diameter
Send your project details
Provide the required capacity, installation location, intended use and any access or compliance requirements. Tricel will confirm the appropriate tank specification, approval status and delivery options.
Next day delivery available on selected in-stock standard tanks. Confirm availability before noon. Subject to location and stock levels.
09
Tank Comparison
One Piece vs Two-Part vs Sectional GRP Water Tanks
The appropriate tank type depends on required capacity, installation access, project programme and plant room constraints. Use this table for initial guidance; confirm the correct type with Tricel technical sales before specifying.
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Requirement
|
One Piece GRP Tanks
|
Two-Part GRP Tanks
|
GRP Sectional Tanks
|
|---|---|---|---|
|
Standard capacity range
|
45 L – 16,000 L
|
Intermediate range; between one piece and sectional
|
1,000 L – 4 million+ litres
|
|
Access requirement
|
Clear route required: Complete tank delivered as one unit; doorway and route must accommodate
|
Partial access: Delivered in two halves; each half must fit through the access route
|
Restricted access: Individual panels transported via narrow corridors, stairwells and lifts
|
|
On-site assembly
|
None required; position and connect
|
Two halves bolted together on site
|
Full assembly by Tricel-trained crews; EFB, IFB or TIF
|
|
Programme impact
|
Shortest installation time; next day delivery available on selected stock
|
Short; assembly of two halves on site
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Longer; dependent on tank size and site conditions
|
|
Plant rooms
|
Suitable where access allows the complete tank to be positioned
|
Partial access: Useful where standard one piece cannot be moved in but access for two halves is achievable
|
TIF for constrained rooms: TIF option for heavily restricted plant rooms
|
|
Replacement projects
|
Suitable where access allows the original tank to be removed and the new tank positioned
|
Useful where the replacement route is partially restricted
|
Common choice: Panel-by-panel removal and replacement in the same space
|
|
CAT5 option
|
Yes
|
Yes
|
Confirm at spec stage
|
10
Project Experience
One Piece GRP Tank Project Experience
Tricel one piece GRP tanks have been installed across domestic, commercial, healthcare and industrial projects throughout the UK.
Food Production Sector — 50 Custom One-Piece Water Tanks
Tricel Water manufactured and installed 50 custom-built GRP one-piece water tanks (dimensions: 2000 x 1200 x 1100mm). Each tank was hygienic, corrosion-resistant, WRAS-approved, and designed with dual manways for safe and easy access.
Special educational needs school — LPCB sprinkler tank
LPCB-approved sectional GRP sprinkler tank installed at a special educational needs school to BS EN 12845 and BS 9251. Installation completed with minimal disruption on a sensitive site with restricted access.
Infrastructure project — large-capacity GRP sectional tanks
GRP water tanks (8m × 7m × 4m) manufactured and installed for two HS2 Green Tunnel sites at Greatworth and Chipping Warden, as part of the UK’s largest current infrastructure project.
11
Related Resources
Plan Your One Piece GRP Tank Project
Products
Compliance & Installation
12
FAQs
GRP One Piece Water Tank FAQs
Common questions from engineers, M&E contractors, facilities managers and specifiers.
What is a GRP one piece water tank?
A GRP one piece water tank is a cold water storage tank manufactured as a single moulded glass reinforced plastic unit. It has no internal joints, seams or panel interfaces — unlike sectional or two-part tanks — which simplifies cleaning and reduces maintenance requirements. Tricel GRP one piece water tanks are manufactured to BS EN 13280:2001, are available WRAS approved for potable cold water storage, and come in insulated and uninsulated versions with AG and Cat 5 AB air gap options. Standard sizes range from 45 to 16,000 litres; bespoke options are available.
What sizes do GRP one piece water tanks come in?
Tricel GRP one piece water tanks are available from 45 litres to 16,000 litres in the standard range. Bespoke sizes are available where standard dimensions do not meet project requirements. Full external dimensions, connection positions and weight data are available in the Tricel water tank sizes reference. Next day delivery is available on selected in-stock sizes when ordered before noon, subject to location and availability.
Are GRP one piece water tanks WRAS approved?
Yes. Tricel GRP one piece water tanks are WRAS approved for potable cold water storage. WRAS approval applies to the tank as manufactured; the full installed system — including fittings, pipework and connections — must also use WRAS-approved components to constitute a WRAS-compliant system. Insulated tanks are rated for potable water stored up to 23°C under WRAS approval. WRAS documentation is available on request.
What is the difference between an AG air gap and a Category 5 AB air gap?
An AG air gap provides mains water protection from fluid categories 1 to 4. The float valve is fitted within the body of the tank at the standard lid arrangement. A Category 5 AB air gap features a raised float valve housing with a spillover weir fitted on top of the lid. This provides the highest level of mains backflow protection — fluid category 5 — and is required where the downstream system presents a category 5 risk to the public supply. The required fluid category must be confirmed with the water supplier or a water regulations inspector at design stage.
Do GRP one piece tanks need to be insulated?
Insulation is required for potable cold water storage under current water regulations. Insulated GRP one piece tanks from Tricel are supplied with 25mm CFC-free PU foam insulation encapsulated within the GRP laminate on all sides and the lid. Insulation maintains water temperature below 20°C for cold supply, reduces the risk of freezing and supports Legionella risk management. Uninsulated tanks are used for process water or non-potable applications where temperature control is not a regulatory requirement.
What standard are GRP one piece tanks manufactured to?
Tricel GRP one piece water tanks are manufactured to BS EN 13280:2001 — the British and European standard for cold water storage tanks manufactured from glass reinforced plastics. This standard specifies requirements for materials, dimensions, structural performance, insulation, testing and marking. All Tricel one piece tanks are tested and approved to meet these requirements.
When should I use a one piece tank rather than a two-part or sectional tank?
A one piece GRP tank is the most straightforward and quickest-to-install option where:
- The access route to the installation point is clear and the complete tank can be moved into position
- The required capacity is within the standard range (45 to 16,000 litres)
- Programme requirements benefit from next day delivery on selected in-stock sizes
Where access is restricted — narrow doorways, stairwells or constrained plant rooms — or capacity requirements exceed 16,000 litres, a two-part or GRP sectional tank should be considered instead.
When should I use a one piece tank rather than a two-part or sectional tank?
Next day delivery is available on selected in-stock Tricel GRP one piece water tanks when ordered before noon, subject to location and product availability. Orders placed after noon are processed for the following business day. Delivery to Scotland, Northern Ireland, within the M25 and offshore islands may be subject to different delivery terms; confirm at the time of order. Availability varies depending on demand and stock levels.
Can GRP one piece tanks be used to store chemicals?
GRP is resistant to many chemicals and is suitable for a range of process and chemical storage applications. Tricel uses specialist resins that enable the storage of mild and aggressive chemicals in some tank configurations. Suitability depends on the specific chemical, concentration and temperature. Chemical compatibility must be confirmed at the specification stage before an order is placed.
What float valve size do I need for a GRP one piece water tank?
Float valve sizing is determined by the incoming mains supply diameter. As a general guide, a 25mm incoming mains requires a 1-inch float valve. The overflow should be sized to suit the float valve specification. Where Tricel supplies the float valve and overflow with the tank, sizing is confirmed at the time of order. If in doubt, contact Tricel technical sales to confirm the correct specification for your system.
Tricel Technical Sales
Ready to specify a GRP one piece water tank?
For standard stock sizes with next day delivery, order or call directly. For bespoke dimensions, Cat 5 configurations, WRAS documentation or specific compliance requirements, send your project details and Tricel will confirm the right specification.
This product 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.
