What Is a Sectional Water Tank? Types, Benefits and How to Choose

What is a sectional water tank used for?

A sectional tank stores the water a building or site needs, in one tank of the required capacity, as a reserve for when the mains supply fails or its pressure drops.

• Drinking and domestic water: housing, hospitals, schools, public buildings.
• Fire water: a reserve kept for the fire protection system; see how it is sized in our tank sizing guide.
• Process and irrigation water: industry, agriculture, livestock farms, construction sites.

The tank is usually paired with a booster set or pump system, or a fire pump set for fire water. Aquasan makes all three at its own plant in Malatya, Turkey; see our projects.

How does a sectional tank work?

A sectional tank is built from standard pressed panels bolted together on site; no welding is needed, and the same panel family builds anything from small tanks to very large ones. In an Aquasan GRP tank:

• Convex (domed) floor panels let the water pressure in a full tank squeeze the joints tighter.
• Embossed wall panels add stiffness; half panels set the height in 0.5 m steps.
• Internal stay rods tie opposite walls together and balance the water pressure.
• A drain panel at the lowest point lets the tank empty completely, and a partition panel can split it into two compartments.

GRP joints are sealed with PVC foam tape that stays flexible in the cold. The tank stands on a hot-dip galvanized steel skid over a concrete base, with flanged or threaded inlet, outlet, overflow and drain connections. See our installation guide.

Sectional, modular, panel or prismatic tank: is there a difference?

In everyday use, no: "sectional", "modular" and "panel tank" all describe a tank bolted together from standard panels. "Prismatic" describes the rectangular (box) shape; in Turkey most tanks sold under this name are bolted sectional panel tanks. Because the term refers only to the shape, as opposed to a cylindrical tank, a one-piece rectangular tank is prismatic but not sectional. Steel versions are often called pressed steel tanks, and GRP is also sold as FRP or fibreglass.

The European standard for GRP tanks, EN 13280:2001, draws the same line. According to the British Standards Institution (BSI) listing, it covers glass fibre reinforced cisterns of one-piece and sectional construction for storing cold water above ground.

Types of sectional water tank: GRP, galvanized and stainless steel

Sectional water tanks come in three main materials, all bolted together from panels:

Feature	GRP	Galvanized steel	Stainless steel
Material	Glass fibre reinforced polyester composite	ST 37 steel, hot-dip galvanized	AISI 304 / 316 L stainless steel
Panel size	1,000 × 1,000 mm (half panel 1,000 × 500 mm)	1,080 × 1,080 mm	1,080 × 1,080 mm
Tank height	1.0–5.0 m in 0.5 m steps	540–4,320 mm in 540 mm steps	540–4,320 mm in 540 mm steps
Key strengths	Light-proof, no algae growth, suitable outdoors; optional insulation	High strength, economical	Highest hygiene, corrosion resistance
Suitable for	Drinking, domestic, fire and process water	Non-potable uses such as fire and process water	Drinking and domestic water and other uses where hygiene matters

Source: Aquatank Product Catalogue 2026, pp. 4, 5, 8, 11, 14–16 and 21.

Choose a GRP sectional tank for outdoor sites or where insulation may be needed, a stainless steel tank where hygiene comes first, and a galvanized steel tank for non-potable uses where strength and budget matter. More detail: GRP vs stainless vs galvanized, what is a GRP water tank and the Aquatank range.

Sectional water tank sizes at a glance

Sectional tank dimensions follow the panel module: 1,000 × 1,000 mm panels for GRP and 1,080 × 1,080 mm panels for galvanized and stainless steel, with half panels setting the height. Volume is length × width × height, and 1 m³ of water weighs about one tonne.

• GRP: panels 1,000 × 1,000 mm (half panel 1,000 × 500 mm), height 1.0–5.0 m in 0.5 m steps. Plan dimensions follow the 1 m panel module; confirm intermediate sizes for your project (catalogue pp. 11, 13). A 3 × 2 × 2 m GRP tank, for example, has a gross volume of 12 m³.
• Galvanized and stainless steel: length and width in multiples of 108 cm, height 540–4,320 mm in 540 mm steps. The standard range runs from 1.26 m³ (108 × 108 × 108 cm) to 90 m³ (648 × 432 × 324 cm); a 10 m³ tank measures 216 × 216 × 216 cm.

Custom sizes are made to order. Leave at least 500 mm between the tank and walls, columns and the ceiling. See the sectional tank sizes guide for full tables.

Advantages and limitations of sectional tanks

The main advantage of a sectional tank is that a large tank can be carried piece by piece into tight spaces and built in place.

Advantages

• Access: panels pass through narrow doorways into basements and plant rooms a one-piece tank could not enter.
• Flexible footprint: the tank is sized to the room; GRP tanks can also be L- or U-shaped and built around columns.
• Partitioned tanks: drinking and fire water can share one tank, which saves the 1 m gap separate tanks need. In our catalogue example, two separate tanks hold 12 tonnes in total; one partitioned tank on the same area holds 16 tonnes.
• Repair and climate: steel panels can be replaced individually, and insulated GRP panels suit very hot or cold regions.

Limitations

• Base and clearance: a concrete base, a steel skid and at least 500 mm of space around the tank are needed.
• Workmanship: watertightness depends on correctly fitted joints, so the installer's experience matters.
• Material limits: galvanized tanks are not recommended for drinking or domestic water; GRP tanks are designed for water normally below 30 °C, at most 50 °C.
• Maintenance: periodic cleaning and disinfection; see the cleaning and maintenance section of our drinking water tank guide.

Sectional vs concrete and one-piece plastic tanks

A sectional tank is assembled on site from factory-made panels, a concrete tank is cast in place, and a one-piece plastic tank arrives ready-made.

Criterion	Sectional panel tank	Reinforced concrete tank	One-piece plastic tank
Size	Sized to the room in panel multiples	Fixed at design stage; hard to change later	Limited to the maker's standard models
Getting it in place	Panels pass through narrow doors	Planned while the building is constructed	The whole tank must fit through the door
Large volumes	One tank, more panels	Possible; designed with the structure	Usually several tanks connected together

Plastic tanks suit small volumes and concrete suits structures planned with the building; for existing buildings, tight spaces or large volumes, a sectional tank is usually the better fit.

How to choose a sectional water tank

The right sectional tank is chosen by looking at capacity, use and the installation space together:

1. Capacity: daily consumption times the days of reserve you want, plus fire water if required; see the tank sizing guide.
2. Material: GRP or stainless steel for drinking water; any of the three for fire and process water.
3. Location: indoors, rooftop or outdoors; ask for insulation in extreme climates.
4. Space and access: measure the room and the door the panels will pass through.
5. Documents and service: for drinking water, ask for current documents showing the material is suitable for contact with drinking water; confirm installation, warranty and spare parts.

Aquasan installs, tests and commissions its tanks with its own teams, with a 2-year product warranty (catalogue pp. 3, 18). For our documents, see the Certificates page; for price factors, see the price guide, or send your project details through the quote form.