Rainwater Harvesting

Valuable drinking water is much too expensive for flushing toilets and irrigating gardens. Therefore, rainwater harvesting is not just sensible, it also has ecological and economic advantages:

Carat Underground Rainwater Tank Installation

Graf Carat S Underground Tank

Graf Carat S TankThe new tank generation of Carat rain-water underground tanks have been specially developed for rain-water harvesting.

Logistical advantages of the Carat

The Carat tank consists of two half shells which can be stacked on top of each other, allowing multiple tanks to be stacked on a single pallet for shipping. For example, it is possible to stack five 6,500 ltr Carat tanks, or nine 2,700 ltr Carat tanks on a single pallet. A standard 40 ft. shipping container can therefore hold a total tank volume of up to 130,000 ltrs. The tanks unique stacking feature directly reduces transport costs and environmental impact from vehicle emissions, whilst allowing shipments to any destination in the world. 

Easy and safe assembly

  • The patented quick connection, allows the Carat tank to be assembled without screws in only few minutes. Disassembly is possible at any time.
  • The first-class EPDM material used in the profile sealings (illustrated in yellow), has been laboratory tested to last more than 25 years.
  • The centering bolt assures the accurate and easy assembly of the two half shells preventing any leaks


  • The global innovation – the new tank generation of the Carat rainwater underground tanks have been specially developed for rainwater harvesting
  • The Carat tank can be individually tailored to your needs as a garden or house tank using the modular system
  • For frost-proof installation in the ground
  • Groundwater stable up to the middle of the tank due to extremely stable construction (2,500 and 3,500 l up to top edge of tank)

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