A GRP water tank is a sectional tank built from glass reinforced plastic panels bolted together on site; in Turkish the same material is called CTP. Aquasan's hot-press moulded GRP panels measure 1,000 × 1,000 mm, are opaque so no algae forms inside, and are used to build tanks 1.0 to 5.0 m high in 0.5 m steps.
Contents
- GRP tank meaning: what does GRP stand for?
- How hot-pressed GRP panels are made
- Key properties of GRP water tanks
- GRP panel specifications
- Panel sizes, tank heights and capacity
- Insulated GRP panels
- Are GRP water tanks safe for drinking water?
- Where GRP sectional tanks are used
- Maintaining a GRP water tank
- Frequently Asked Questions
GRP tank meaning: what does GRP stand for?
GRP stands for glass reinforced plastic, sometimes written as glass-fibre reinforced plastic. The same material is also called FRP or fibreglass, and CTP in Turkish: a polyester resin composite reinforced with glass fibre.
A GRP sectional tank (also called a GRP panel tank) is bolted together on site from standard moulded panels, unlike a one-piece tank that is delivered as a single unit. It can therefore pass through narrow doorways and be built to the size the site needs (catalogue p. 4). For how sectional tanks work in general, see What is a sectional water tank?
An Aquasan GRP tank consists of wall, floor, roof, manhole and drain panels, internal stay rods that tie opposite walls together, galvanized corner profiles, a hot-dip galvanized steel skid on a concrete base, and fittings such as the manhole cover, air vent, ladders and pipe flanges. No welding is needed (p. 10).
How hot-pressed GRP panels are made
Aquasan GRP panels are made from unsaturated polyester reinforced with chopped glass fibre and cured under pressure in moulds heated to 150 °C on high-tonnage presses (p. 5). The result is a panel that is smooth and fully cured on both faces.
Each panel type is pressed in a form suited to its job (p. 11). Wall panels are embossed for stiffness and roof panels are cross-ribbed and opaque. Floor panels are convex: in a full tank, water pressure pushes them down and compresses the flange joints, improving the seal, whereas with flat floor panels the same pressure forces the joints open.
The main alternative is hand lay-up, where resin and glass fibre are applied to a mould by hand. With hot pressing, the mould sets the panel form and curing temperature, and one standard panel family covers small to very large tanks (p. 11). Joints are sealed with PVC foam tape (p. 12).
Key properties of GRP water tanks
A GRP water tank is opaque, resists UV and corrosion, and its material is much lighter than steel:
- Opaque and algae-free: panels and the closed roof block light, so no algae forms inside (pp. 5, 10).
- Outdoor use: UV resistant with low thermal conductivity, for very hot and very cold climates (p. 6).
- No corrosion: panels do not corrode and keep their shape for many years (p. 6).
- Light material: a density of 1.8 kg/dm³ against 7.85 kg/dm³ for steel, which the catalogue describes as a quarter of the weight of steel (pp. 5, 8).
- Flexible layouts: rectangular, L and U shapes, with column penetrations (p. 9).
GRP also has limits: water should normally stay below 30 °C, with a maximum of 50 °C (p. 12). In the catalogue's own comparison chart, the Aquasan GRP panel tank rates "very good" for watertightness, maintenance, corrosion resistance and installation, "good" for water quality and durability, "fair" for transport and "poor" for recycling (p. 7). See our GRP vs stainless vs galvanized tank comparison.
GRP panel specifications
Aquasan GRP panels have a tensile strength of 99.5 MPa and a flexural strength of 165 MPa, with a glass fibre content of 32.1%.
| Property | Value |
|---|---|
| Tensile strength | 99.5 MPa |
| Flexural strength | 165 MPa |
| Modulus of elasticity | 13,800 MPa |
| Barcol hardness | 70 |
| Density | 1.8 kg/dm³ (steel 7.85) |
| Water absorption | 0.01% |
| Glass fibre content | 32.1% |
| Light transmission | None |
| Heavy metals | Not detected |
| pH (20 °C) | 6.9 |
| Phenol | Not detected |
Source: Aquatank Product Catalogue 2026, p. 8.
The tank withstands 60 m/s wind even when empty, and the roof carries 200 kgf/m² against a design snow load of 60 kgf/m² (about 30 cm of snow). Seismic coefficients are Kh = 2/3 and Kv = 1/3, and side wall deflection stays within 1% of height after 48 hours full (p. 12).
Panel sizes, tank heights and capacity
Aquasan GRP panels are 1,000 × 1,000 mm, with 1,000 × 500 mm half wall panels (pp. 5, 11). Width and length follow the 1,000 mm panel module, and height is chosen from 1.0 to 5.0 m in 0.5 m steps (catalogue pp. 5, 8, 11). The catalogue's partitioned-tank example also shows 2 × 1.5 × 2 m tanks (p. 13), so half-metre plan dimensions may be possible; confirm the exact footprint for your project with us.
The catalogue does not list fixed GRP capacities; each tank is sized to the space and demand. Volume is length × width × height, and 1 m³ holds roughly 1 tonne of water. See sectional tank sizes and our water tank sizing guide.
Insulated GRP panels
An insulated GRP panel is a three-layer panel with 25 mm of polyurethane foam between the GRP panel and a protective cover (p. 12). Made on request for very hot or very cold regions, it prevents outside condensation and limits temperature change in the stored water; the foam contains no CFCs or HCFCs (pp. 5, 8).
| Tank type | Thermal conductivity (kcal/m·h·°C) | Overall heat transfer, water–panel–air (kcal/m²·h·°C) |
|---|---|---|
| Steel | 37.0 | 24 |
| GRP (uninsulated) | 0.15 | 5 |
| GRP (insulated) | 0.02 | 1 |
Source: Aquatank Product Catalogue 2026, p. 12.
Are GRP water tanks safe for drinking water?
GRP tanks are commonly used for drinking water, provided the panel material suits potable water and the tank is kept closed and cleaned regularly. The catalogue states that the food-contact suitability of the GRP panels is documented by laboratory reports (pp. 6, 21). It also lists no heavy metals or phenol detected and a pH of 6.9 at 20 °C (p. 8).
In Turkey, the Ministry of Health's Regulation on Water Intended for Human Consumption (Official Gazette, 17 February 2005, No. 25730) requires all surfaces in contact with water at every stage up to the point where it is supplied for consumption, and the devices and equipment used in contact with it, to be made of materials that do not impair water quality or harm health (Article 13).
Water quality also depends on the source water, a closed manhole and vent, and periodic cleaning. See our Certificates page, or ask for the documents your project needs with your quote request.
For the other features to look for in a drinking water tank, see our drinking water storage tank guide.
Where GRP sectional tanks are used
GRP sectional tanks store drinking, utility, fire and process water (p. 23) in housing, hospitals, schools and dormitories, public buildings, industry, agriculture and irrigation, livestock farming and construction sites (p. 4).
The tank can go indoors, on a rooftop or outdoors (pp. 5, 23), on a steel skid over a concrete base with 500 mm clearance to walls, columns and the ceiling (pp. 8, 9). A partition panel can split one tank into drinking water and fire water compartments (p. 13); for the pumps, see our fire pump sets.
Maintaining a GRP water tank
GRP tank maintenance means periodic cleaning, disinfection and inspection, and the tank has a manhole, internal ladder and drain panel for this (pp. 10, 18). The floor drains dirty water and sediment fully from its lowest point (pp. 9, 11), and pipework should be supported separately so it puts no load on the tank (p. 13). Panels, gaskets and fasteners are supplied from stock, and Aquasan tanks carry a 2-year product warranty (pp. 3, 18). For drainage, cleaning and maintenance, see our drinking water tank guide; for assembly, see the sectional tank installation guide.
Frequently Asked Questions
What does GRP stand for in water tanks?
GRP stands for glass reinforced plastic, sometimes written as glass-fibre reinforced plastic: a polyester resin composite reinforced with glass fibre. It is also called FRP or fibreglass, and CTP in Turkish. In Aquasan's hot-pressed GRP panels the glass fibre content is 32.1% (p. 8).
What is the difference between a GRP sectional tank and a one-piece tank?
A one-piece tank is moulded and delivered as a single unit. A GRP sectional tank is bolted together on site from standard 1,000 × 1,000 mm panels, so it passes through narrow doorways and can be built in rectangular, L or U shapes to suit the space (pp. 4, 9).
Is a GRP water tank safe for drinking water?
GRP panels are opaque, so no algae forms inside, and Aquasan's catalogue lists no heavy metals or phenol detected and a pH of 6.9 at 20 °C (p. 8). The catalogue states that the food-contact suitability of the GRP panels is documented by laboratory reports (pp. 6, 21). Keep the tank closed and clean it regularly.
Can a GRP tank be installed outdoors or on a roof?
Yes. GRP panels are UV resistant and have low thermal conductivity (p. 6). Under the catalogue's design criteria, the tank withstands 60 m/s wind even when empty and its roof carries a snow load of 200 kgf/m² (p. 12). On a roof, have a structural engineer check the building's load capacity.
Who manufactures GRP sectional tanks?
Many companies make them. Aquasan manufactures GRP sectional tanks at its own plant in Malatya 1st Organized Industrial Zone, Turkey, and installs them with its own teams (pp. 2, 18). To discuss a project, request a quote with the capacity and site details.
Get a quote for your project
Share the required capacity (m³), application and location; our engineers will reply with a recommended panel type, size and material.