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Sirris designs composite tanks for Eloy Water

In 2014-15, Belgian water treatment specialist Eloy Water commissioned Sirris to develop a set of new wastewater treatment tanks made of thermosetting composite, to supplement its range of traditional concrete tanks. Its aim was to be able to offer reliable and affordable treatment plants that are easier to produce, store, handle and install.
  • Eloy Water is developing a new range of wastewater treatment plants 
  • Sirris designed the key components of the plants: composite tanks 
  • These tanks meet strict requirements in terms of mechanical strength, weight and shape
  • Sobelcomp produced the prototypes and will mass produce the tanks


Founded in 1965, Belgian company Eloy Water specialises in wastewater treatment and rainwater recovery, for both households and communities. Based in Sprimont, it designs, manufactures, distributes and maintains domestic wastewater treatment plants, among other products. 

“Thanks to the composite materials, a new range of lightweight treatment plants has been born.”

From concrete to composite

Every year, Belgian company Eloy Water manufactures, transports and installs thousands of wastewater treatment plants for individual houses or housing estates. Each plant includes a concrete tank holding up to 20,000 litres. For ease of handling, Eloy Water has supplemented its concrete range with a range of tanks made of composite material, which is lighter and more versatile. 

Multiple requirements: composite solutions

The Sprimont-based firm asked Sirris to design a tank made of thermosetting composite material, meeting the same requirements as traditional concrete tanks. The tank bases and lids had to be interchangeable across all models in the range. The tanks also needed to be stackable for ease of storage and transport. 

Four men only

Sirris drew on its expertise in composites to design and size all elements of the tanks according to these various requirements. Industrial composites processor Sobelcomp monitored the feasibility of the concept throughout the design process, produced the prototypes according to Sirris’s instructions, and will mass produce the tanks. The new tanks are lighter, with the reference tank  (6,000 litres) weighing less than 200 kg and only requiring four men to handle it. A new range of lightweight plants is born!