Fat Boy Septic Tanks are rotationally moulded using a mix of recycled and prime grade polyethylene. This formulation combined with the tank’s spherical design provides exceptional strength and durability. Our 600 gallon tank contains a second compartment, inspection port and effluent filter, this ensures that no solids enter your soakaway.  Tanks can also be joined to create larger systems. Our tanks are easy to transport and install. Installation instructions are included with each purchase.


  • 800 US Gallon / 3028 L – Single Compartment with Filter (Maximum No. of Users 12)
  • 600 US Gallon / 2271 L -Double Compartment with Filter (Maximum No. of Users 7)
  • 500 US Gallon / 1895 L – Single Compartment – no Filter (Maximum No. of Users 5)



Fatboy Installation instructionsClick Here or image to download

FA Questions:

What is a digestor?

A digester is a secondary treatment unit that treats effluent from the septic tank. Bacteria naturally reduce the sludge volume during the digestion process and may either require the use of oxygen (aerobic digestion) or not (anaerobic digestion).

The most obvious results of this treatment include odour & colour elimination. This tank can be used as an alternative where soakaways are not an option and the effluent can be discharged into a rubble drain for final treatment.

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