The Multi-siphon unit from ACT-WISY is designed specifically for use in rainwater storage tanks. It is fitted inside the tank and connected to the sewer drain pipe (DN 100) in the tank. This made of tough ABS plastic. The unit is effectively a ‘U’ bend, providing a water seal. This acts as a barrier to unpleasant smells from the drain that connects to the overflow, which could otherwise taint the water.

The unit also performs the important function within the tank of removing the floating debris from the surface of the water. This is achieved by the units’ inlet, which is so shaped that when overflow conditions occur the water is ‘skimmed” rapidly into the horizontal opening.

The passive rodent guard (vermin protection)is made of stainless steel; it can easily be removed for maintenance purposes.




  • Multifunctional overflow unit
  • Made of impact-resistant ABS plastic.
  • Connects to an overflow pipe.
  • Removes surface debris.
  • No drain smells.
  • Prevents rodents from entering into the tank.
  • Corrosion proof.
  • Optional anti-backflow device.
  • Optional anti-vermin device.
  • Horizontal opening maximizes skimming effects.



      • drain odor elimination.
      • vermin protection.
      • backflow protection.
      • overflow with skimming effect.
      • pipe protection in case of backflow.
      • gas barrage.

        Different types of Multisiphon units are available :

        Multisiphon with drain backflow protection
                        Without vermin protection US 10 04
                        With vermin protection US 10 02
        Multisiphon without drain backflow protection
                        Without vermin protection US 10 05
                        With vermin protection US 10 03