There are many ways to store liquids and the final choice depends on several main factors. There are tanks available on the market made of: reinforced concrete, steel, polypropylene, polyethylene. However, to transport a 100m³ tank on one pallet for several thousand euros and “assemble” it in 30 minutes – it’s only possible with the technology of highly durable technical fabrics.

Pillow flexible tanks

Pillow flexible tanks

There are many ways to store liquids and the final choice depends on several main factors. There are tanks available on the market made of: reinforced concrete, steel, polypropylene, polyethylene. However, to transport a 100m3 tank on one pallet for three hundred zlotys and “assemble” it in 30 minutes – it is only possible with the technology of highly durable technical fabrics. Flexible tanks for several decades in the world have been increasing the group of their supporters.


As is usually the case, innovative technologies where logistics and simplicity count, start their way in the army. The first rubberized fabric tanks appeared in the Allied army during World War II, for the purpose of storing fuel in them.

In later years, there was an increase in ideas for their use and the development of the fabrics themselves. Polyester fabrics coated with plastomers (polyurethane and polyvinyl chloride) appeared. For several decades, flexible tanks around the world have been used to store: wine, drinking water, liquid manure, rainwater, mineral fertilizers, fuels and a number of chemicals.

Flexible tank – pillow: construction

The shape of the flexible reservoir resembles a pillow or a closed bag or balloon. Its shape is formed by a liquid, which is assumed to fill it evenly inside. When filling the tank, its walls rise with the connections. Free-standing “cushions” are usually 1.3 – 1.7 m high.

Flexible tanks can be made of rubber (rubber tanks), but currently in the world they are most often made of special multi-layer fabrics. The inner carrier, mainly responsible for the tear strength, is made of polyester or nylon and a layer of varnishes and plastomers (usually PVC) responsible for UV resistance, tightness and chemical-physical factors. The fabrics are selected depending on the capacity of the tanks and their purpose.

  1. High-tensile polyester backing
  2. Double-sided impregnation layer
  3. Double-sided main shell made of the highest quality PVC
  4. Double-binding primer
  5. Topcoat layer
multi-layer technical fabrics

Example of multi-layer technical fabrics (source: www.sioencoating.com)

Flexible tank: do the pros hide the pros?

As with any product, there are a number of “positive and negative” features. Let’s look at the most important ones:


  • Easy to logistics: it takes up a few percent of its target volume, so we can transport huge volumes with cheap transport. It is lighter than a steel tank.
  • It does not require complex construction works: it is enough to spread it on a level area (meadow, square under the building, floor in the room)
  • Corrosion resistance: The plastic tank has a wide chemical resistance.
  • Economical: A flexible tank typically provides the lowest liquid storage costs per cubic meter
  • Reduced growth of algae and microorganisms: closed form and material impervious to sunlight, reduces the growth of algae inside the flexible tank


  • lifetime: tanks are not as durable as heavy ones made of e.g. stainless steel or concrete. Their service life (depending on the quality of workmanship, materials and purpose) may be from several to several dozen years (water, fertilizers).
  • resistance to mechanical damage: the tank is made of special, super durable technical fabrics. However, by applying some force with a sharp object, it can be damaged faster than a steel tank. However, if a flexible tank is located in a closed, fenced area or under constant monitoring, this minus ceases to exist.

When choosing a flexible tank, it is worth considering all its features. If we plan to invest in the coming years, the several-year (and possibly longer) service life of a flexible tank, combined with its advantages and the lowest storage price per cubic meter, may perfectly match the Investor’s needs.

What to use for?

There are many ideas for the use of flexible tanks, because more and more industries are looking for alternative, reusable and cheaper solutions.

Examples of applications of flexible tanks:

  • Drinking and service water at the construction site
  • “RSM”, ASL fertilizers
  • Slurry
  • Water buffer for extinguishing purposes
  • Emergency sewage storage in the plants
  • Ballasting of buildings and structures
  • Storage of fuels and liquid waste
  • Water supply for field and temporary kitchens
  • There can be a lot of ideas because the tanks are resistant to a number of chemicals

What to look for?

Before we decide to buy a flexible tank, it is worth making sure that the given liquid does not react negatively with the tank jacket. If it is a chemical substance for which we have a safety data sheet – check the recommended packaging and storage in it. If it is a typical liquid (water, fertilizers, oils) – the manufacturer of the tanks usually dedicates products to the most common applications.

Tank material: it is worth comparing the technical parameters of fabrics (manufacturers usually provide: grammage, resistance to tearing or stretching). Note – although the final coating in the tanks compared may be the same, i.e. PVC, the PVC fabric should be dedicated to work in a given chemical environment (there are differences in the production process of PVC fabrics and selected varnishes). If you plan to buy a drinking water tank, ask about the certificates of the tank fabric and components.

Flexible tank manufacturer – it is worth paying attention to the origin of the product, the experience of its manufacturer, but also to the service and technical support it offers.

The growing group of supporters and users of flexible tanks every day proves that it is worth considering, for example, this fluid storage technology. It can be the most economical solution, while ensuring the necessary safety and tightness.

Przemysław Domagalski

CEO of Exflo Sp. z o.o., a regular participant of trainings and workshops on the storage of hazardous substances, certified internal ISO 14001 auditor, co-creator of practical products supporting environmental protection.