Prefab drinking water storage tank

With the continuous growth of population and the expansion of urban and rural areas, efficient water supply management has become increasingly important. One of the key components of any water distribution system is the water storage tank. Among the various types of storage systems, prefabricated cylindrical water storage tanks have been widely used for many years throughout Europe and North America due to their reliability and performance.

Prefabricated water storage tanks have been available in the Iranian market for more than 16 years. Thanks to their numerous advantages, they have become one of the most preferred solutions for water storage applications. A prefabricated galvanized water storage tank typically features a cylindrical steel structure with a metal roof, while a high-quality Aqua or Aquatex waterproof liner ensures the safe and hygienic storage of potable water.

The tank walls are assembled using a bolted panel system, allowing for fast installation and easy transportation. The structure is securely supported by steel columns mounted on a concrete foundation. The tank panels are manufactured from galvanized steel or coated with high-performance zinc polyurethane paint, providing superior corrosion resistance and long service life in various environmental conditions.

Depending on the project requirements, prefabricated water tanks can be equipped with a steel roof featuring a manhole access or with different types of polymer roofs. In addition, as the construction costs and project duration of conventional concrete reservoirs continue to increase, prefabricated galvanized tanks and modular water storage tanks have become the preferred choice for modern water infrastructure projects, offering significant advantages in terms of cost-effectiveness, rapid installation, durability, and ease of maintenance.

Components of the Aquatex Prefabricated Potable Water Storage Tank:

Tank Wall Structure

The wall of the Aquatex prefabricated cylindrical water storage tank (also known as a galvanized modular water tank) is manufactured from high-strength structural steel panels with either a hot-dip galvanized coating or a high-performance epoxy coating. These prefabricated panels are delivered to the project site on pallets and assembled using a bolted connection system, allowing for fast, efficient, and reliable installation.

The tank wall is the primary structural component of the storage system. It is engineered to withstand hydrostatic pressure from the stored water, roof snow loads, wind loads, and other external forces while maintaining long-term structural integrity. The protective coating applied to the steel panels is selected according to the environmental and climatic conditions of each project. For most standard environments, hot-dip galvanized steel is the preferred choice. The galvanized coating should provide a minimum zinc coating weight of 200 g/m² to ensure excellent corrosion resistance and long service life. For this reason, high-strength structural steel with heavy zinc coating is used in the manufacturing process.

Because water storage tanks must continue to perform safely under extreme environmental conditions and natural disasters, every prefabricated galvanized tank is designed in accordance with established structural engineering principles and international design standards. The tank walls are reinforced with vertical steel stiffeners that are securely anchored to the concrete foundation. These stiffeners extend from the top to the bottom of the tank wall, increasing resistance to lateral loads, wind forces, and roof snow loads. The number, dimensions, and spacing of the stiffeners are determined through detailed structural calculations based on the tank size and project requirements.

In addition to structural design, the quality of the construction materials plays a critical role in the service life of the tank. All wall panels are manufactured from premium high-strength structural steel and protected by hot-dip galvanizing with a high-zinc coating, providing outstanding resistance to corrosion, humidity, and harsh environmental conditions.

For projects requiring enhanced corrosion protection, polyurethane primer coatings or advanced three-layer protective systems consisting of zinc, phosphate, and polyurethane can be applied. These coating systems provide exceptional resistance against high humidity, acidic soils, and aggressive industrial environments while significantly extending the operational life of the tank. The final exterior finish can also be supplied in the customer's preferred color.

To further increase the structural rigidity of the tank, the steel panels are formed with a corrugated (wave-profile) design, improving strength while reducing weight.

Due to their steel construction, these systems are commonly referred to as prefabricated steel tanks, bolted steel tanks, cylindrical steel water tanks, or prefabricated galvanized tanks. This technology was originally developed in the Netherlands under the Aqua tank concept before being introduced to the Iranian market. Haft Gardoon Pars, as the first domestic manufacturer of prefabricated cylindrical water storage tanks in Iran, localized this technology using advanced CNC machining and modern roll-forming equipment to meet local engineering standards and environmental conditions.

Because the tank panels are connected using high-strength bolts, these systems are also known as bolted steel water tanks. They are available in multiple configurations, including EcoTank models and conical roof prefabricated tanks, to suit a wide range of municipal, industrial, agricultural, and fire protection applications.

Aquatex Waterproof Liner

The Aquatex waterproof liner is one of the most critical components of a prefabricated lined water storage tank or galvanized modular water tank, as it is directly responsible for the safe storage of potable water. To ensure long-term performance and maintain drinking water quality, the liner must be manufactured from premium-grade materials with exceptional durability and hygienic properties.

In addition to superior material quality, the liner must remain highly flexible so that it can accommodate minor ground settlement, structural movement, or seismic activity without tearing or losing its watertight integrity. It must also provide excellent resistance to extreme temperatures, ultraviolet exposure, and the chlorine commonly found in treated drinking water.

Several types of waterproof liners are used in prefabricated steel tanks, including Butyl Rubber, EPDM, Polyethylene (PE), and PVC. However, for the environmental conditions found in most regions and for long-term potable water storage, the Aqua® / Aquatex® liner is considered the preferred solution.

The Aquatex liner offers outstanding resistance to harsh environmental conditions while allowing simple on-site repair by trained technicians whenever required, minimizing maintenance costs and downtime. It is designed to operate reliably within a temperature range of –30°C to +70°C, making it suitable for a wide variety of climates.

Manufactured using advanced nanotechnology, the Aquatex liner complies with ISO 21145 and ISO/TS 80004 standards. It is available in several colors, including blue, white, green, and black, allowing flexibility to meet different project requirements.

For potable water storage applications, only Food-Grade PVC liners certified for drinking water use should be installed. The Aquatex potable water liner complies with Drinking Water Standard 1053 and has been approved by KIWA Netherlands, ensuring complete safety for human consumption. Thanks to its protective nano-layer technology, the liner does not alter the taste, odor, or quality of the stored water, preserving its purity throughout its service life.

Aquatex liners are manufactured using advanced German production equipment and are welded into a single seamless membrane using high-frequency (HF) welding technology, creating exceptionally strong and leak-proof joints.

Because these tanks utilize the Aqua® / Aquatex® liner system, they are commonly referred to as Aqua Tanks or Aquatex Triple-Layer Water Storage Tanks. One of their most significant advantages is the ability to repair the liner quickly and efficiently on-site without dismantling the tank structure.

The liner's smooth, non-porous surface inhibits the growth of algae and bacteria, greatly reducing biofilm formation and minimizing maintenance requirements. Unlike conventional concrete reservoirs, Aquatex-lined tanks generally do not require annual cleaning under normal operating conditions.

In addition, the Aquatex waterproof liner used in prefabricated galvanized water tanks is NSF certified, confirming its compliance with internationally recognized standards for drinking water safety and public health.

Metal Roof System

For potable water storage tanks, the structure must be completely sealed to prevent the entry of dust, insects, birds, and other external contaminants. For this reason, prefabricated cylindrical water storage tanks are equipped with a high-strength steel roof that protects the stored water while maintaining hygienic conditions.

The galvanized modular tank roof is engineered as a robust truss structure designed to withstand heavy snow loads as well as maintenance personnel walking on the roof. The roof is supported by hot-dip galvanized steel trusses, ensuring excellent structural strength, corrosion resistance, and long service life.

The roof assembly includes a manhole access hatch, an external access ladder, and an internal ladder, allowing safe inspection, maintenance, and operation of the tank.

A properly engineered steel roof is designed as a self-supporting dome without any internal support columns. Eliminating interior columns maximizes the usable storage volume, simplifies inspection and maintenance, and prevents obstructions inside the tank. The dome-shaped design also promotes the natural shedding of snow and rainwater, reducing structural loads during winter conditions.

To maintain water quality, the roof is equipped with essential accessories such as a ventilation system that allows controlled air exchange while protecting the tank from external contamination. Additional accessories, including inspection ports, level sensors, lighting systems, and other customized equipment, can be incorporated to meet specific project requirements.

Thermal Insulation and Protective Intermediate Layer

Between the steel wall panels of the prefabricated modular water tank and the Aquatex waterproof liner, an intermediate insulation layer made of thermal foam or high-performance geotextile is installed. This layer acts as a thermal barrier, reducing heat transfer between the external environment and the stored water while helping maintain a stable water temperature.

The type and thickness of the insulation material are selected according to the climatic conditions and operational requirements of each project. By minimizing thermal exchange, the insulation enables reliable operation of the tank in both extremely cold and hot climates.

Under normal environmental conditions, the galvanized steel wall and the Aquatex liner already provide a satisfactory level of thermal resistance. However, in mountainous regions, cold climates, or areas exposed to intense heat, a detailed thermal analysis is performed. The required insulation is determined by calculating the heat transfer rate and the time required for the stored water temperature to change by one degree, ensuring optimal thermal performance and energy efficiency.

A high-strength GTI protective geotextile liner is also installed between the steel structure and the waterproof liner. Manufactured from durable polymer fibers—including polyethylene (PE), polypropylene (PP), and polyamide (PA)—with a nonwoven felt structure, this protective layer performs several important functions:

• Protects the Aquatex liner against abrasion and mechanical damage.
• Prevents wear caused by contact with the steel structure and tank floor.
• Provides additional thermal insulation.
• Reduces heat loss and heat gain through the tank wall.
• Extends the service life of the waterproof liner and the entire storage system.

Because these tanks consist of an outer steel structure, an intermediate protective and insulating layer, and an inner waterproof liner, they are commonly referred to as triple-layer prefabricated water storage tanks or triple-layer modular water tanks, offering superior durability, thermal performance, and long-term protection for potable water storage.

Tank Fittings (Inlet, Outlet, Overflow & Drain System)

Like all water storage systems, a prefabricated cylindrical water storage tank requires a complete piping system consisting of an inlet, outlet, overflow, and drain connection to ensure safe and efficient operation.

• Inlet: Supplies water to the tank from the main water source.
• Outlet: Delivers stored water to the distribution network or point of use.
• Overflow: Prevents overfilling by safely discharging excess water when the tank reaches its maximum capacity.
• Drain: Allows complete emptying of the tank for cleaning, maintenance, and inspection.

The size and configuration of each fitting are determined according to the tank capacity, inlet flow rate, required discharge capacity, and the design specifications of the water distribution system.

To meet different project requirements and customer preferences, tank fittings can be manufactured from a variety of materials, including carbon steel, high-density polyethylene (HDPE), or high-pressure PVC, ensuring compatibility with the intended application and operating conditions.

Tank Access Hatch and Ladder System

The prefabricated cylindrical potable water storage tank is equipped with a lockable roof access hatch (manhole) that provides safe entry into the tank for inspection, maintenance, and cleaning operations. The hatch is installed on the tank roof and features a secure locking mechanism to prevent unauthorized access and protect the stored drinking water from contamination.

For safe access to the roof and the tank interior, the system includes both an external access ladder and an internal ladder. The external ladder is securely mounted to the tank wall and provides convenient access to the roof hatch, while the internal ladder allows maintenance personnel to safely enter the tank when required.

For elevated water storage tanks, the external ladder is fitted with a protective safety cage (ladder guard) to enhance operator safety and comply with industrial safety standards when working at height.

The complete access system is designed to provide safe, convenient, and secure operation while supporting routine inspection, maintenance, and long-term reliability of the water storage tank.

Tank Ventilation System

The prefabricated triple-layer cylindrical galvanized water tank is equipped with a ventilation system designed to maintain proper air circulation inside the tank while safely releasing chlorine gases and excess moisture that may accumulate during normal operation.

The size and number of tank ventilators are determined based on the tank capacity, ventilation requirements, and operating conditions. Proper ventilation helps maintain water quality, balance internal air pressure during filling and emptying, and reduce condensation within the tank.

In hot and humid climates, where water vapor accumulation is more significant, larger or additional ventilators are incorporated into the tank design to provide enhanced airflow and improve moisture control. This contributes to maintaining hygienic storage conditions, extending the service life of the tank components, and ensuring reliable long-term performance.

Optional Exterior Coating System

The exterior coating system of a triple-layer lined cylindrical water storage tank is selected based on the installation location, environmental conditions, and project-specific requirements to ensure maximum corrosion resistance and long-term durability.

For hot, dry, and desert environments, where humidity is generally low but soils may contain high levels of salts or acidic compounds, an Epoxy Phenolic primer combined with a Polyurethane (PU) topcoat is recommended to provide superior chemical resistance and long-lasting protection.

In regions with high humidity, coastal climates, or aggressive industrial environments, a multi-layer protective coating system consisting of zinc-rich primer, epoxy phenolic intermediate coating, and a polyurethane (PU) finish coat is recommended. This advanced coating system provides exceptional resistance against corrosion, moisture, ultraviolet (UV) radiation, and harsh environmental conditions.

For projects located in moderate climates with normal environmental exposure, hot-dip galvanized steel with a high-zinc coating provides an economical and highly effective corrosion protection solution.

To ensure the most suitable coating system is selected, customers are encouraged to provide detailed information about the project location and environmental conditions during the design and quotation stage. This enables Haft Gardoon Pars to recommend the optimal corrosion protection system for maximum performance, durability, and service life.

Additional Optional Accessories

A wide range of optional accessories and customized equipment can be supplied and installed for prefabricated galvanized water storage tanks according to the specific requirements of each project. These accessories may include backfill bags, grounding cables, additional valves, extra epoxy coatings, and any other equipment requested by the customer.

If required, advanced systems such as telemetry equipment, internal pump support frames for submersible pumps, electrical control panels with hydraulic water level indicators, and additional valve assemblies can also be integrated and commissioned on Aquatex prefabricated water tanks.

These customized solutions allow the tank system to be adapted to various operational conditions, improving monitoring capabilities, safety, automation, and overall performance.

Combined Potable Water and Firefighting Water Storage Application

The Aquatex prefabricated water storage tank can be designed and utilized as a dual-purpose storage system for both potable water supply and firefighting water storage simultaneously.

This combined application is commonly used in oil and gas facilities, industrial sites, and remote operational camps, where the Aquatex triple-layer tank must provide safe drinking and domestic water while also ensuring an emergency water supply for fire protection systems.

By modifying the outlet piping configuration, the Aquatex water tank can be equipped with a dual outlet system, allowing separate connections for potable water distribution and firefighting requirements. This customized design provides an efficient and space-saving solution while maintaining reliable access to water during normal operation and emergency situations.

The dual-purpose Aquatex tank offers significant advantages for critical facilities by reducing infrastructure requirements, optimizing site space, and providing a dependable water storage solution for both daily consumption and emergency fire suppression needs.

Maintenance and Repair of Aquatex Triple-Layer Steel Water Tanks

The components of Aquatex triple-layer prefabricated steel tanks are designed for easy inspection, repair, and replacement. Haft Gardoon Pars, as one of the leading manufacturers of prefabricated cylindrical water storage tanks and Aquatex tank systems, has developed the technology and production capability to manufacture all structural components of Aquatex steel tanks using advanced machinery and modern manufacturing equipment.

During maintenance operations, structural components are initially inspected and repaired whenever possible. If replacement is required, damaged parts can be easily removed and replaced without the need for major reconstruction. During periodic inspections, if the operator observes any signs of moisture, leakage, corrosion, or unusual conditions, it is recommended to immediately contact the tank manufacturer. Early action with minimal repair costs can prevent further damage and extend the service life of the tank. Haft Gardoon Pars provides repair and replacement services to quickly restore the tank to normal operating conditions.

Maintenance of Aquatex Waterproof Liner

Proper maintenance of the Aquatex waterproof liner is essential for preserving the quality of stored potable water and ensuring long-term performance. During tank cleaning procedures, operators should enter the tank only with suitable plastic safety boots and must avoid using sharp tools or objects that could damage the liner surface.

When properly maintained and operated according to the manufacturer's guidelines, the Aquatex liner can achieve a service life of more than 70 years. Following the recommended maintenance instructions is essential to maximize the durability and reliability of the liner system.

Maintenance of Steel Structure and Components

For maintaining the steel wall panels and other metal components, the main requirement is to immediately repair any water leakage to prevent possible corrosion or deterioration of the structure. The tank walls are manufactured from high-strength steel with a durable protective coating; however, proper inspection and maintenance significantly increase the service life of all metal components.

In areas with severe humidity, coastal conditions, or aggressive environments, the steel panels should be protected not only with galvanization but also with an additional epoxy coating system to provide enhanced corrosion resistance.

Recommended Long-Term Solution

For permanent applications, harsh environments, and locations requiring minimum maintenance costs, the most suitable Aquatex prefabricated tank system consists of:

• High-strength galvanized steel wall panels.
• A three-layer protective coating system including zinc-rich primer, zinc phosphate, and polyurethane (PU) topcoat.
• Aquatex waterproof liner with nano-coating technology and anti-peeling properties.

This advanced configuration provides excellent durability, low maintenance requirements, and outstanding performance under the climatic conditions and operational requirements commonly found in Iran.

The main difference between cylindrical galvanized prefabricated tanks and rectangular galvanized tanks is their external shape and structural design. However, rectangular galvanized tanks generally require higher maintenance costs compared with cylindrical systems.

The Aquatex prefabricated tank is considered an ideal alternative to traditional concrete reservoirs due to its fast installation, lower overall cost, relocation capability, easy repair process, and simple maintenance requirements. These advantages make it a suitable solution for municipal and rural potable water storage, industrial water storage, and wastewater applications.

For obtaining technical consultation, pricing information for Aquatex prefabricated tanks and galvanized cylindrical water storage tanks, customers can contact the specialists at Haft Gardoon Pars.

General Maintenance Guidelines for Triple-Layer Cylindrical Tanks

Maintenance of the Aquatex triple-layer cylindrical tank is simple and cost-effective. Any abnormal condition, leakage, or structural change should be reported to the manufacturer of the Aquatex potable water storage tank system as soon as possible.

As a triple-layer tank consists of three protective layers within its wall structure, the most important component is the Aquatex waterproof liner, which plays the primary role in maintaining water quality and ensuring a leak-proof storage environment.

Advantages of Prefabricated Cylindrical Steel Water Tanks with Aquatex Liner

Prefabricated cylindrical steel water tanks equipped with Aquatex liners offer numerous advantages compared with conventional water storage systems, including:

• Fast and easy installation, even in remote and difficult-to-access locations.
• Lower overall cost compared with traditional concrete water reservoirs.
• Long service life and reliable durability under various environmental conditions.
• Low maintenance and repair costs throughout the operational lifetime of the tank.
• No price adjustment or cost escalation during the contract period, providing better project cost control.
• Easy dismantling and relocation capability when required.
• Warranty coverage and after-sales support services.
• Anti-algae and anti-moss liner system to maintain water quality and hygiene.
• Compliance with potable water health and safety standards for drinking water applications.
• High resistance against earthquakes and strong wind loads due to advanced structural design.
• Very low heat transfer coefficient, providing improved thermal stability and reducing temperature fluctuations of the stored water.