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Installation Guidelines




  1. Where ground water or high-water table exists, we do not recommend installing an underground water tank.
  2. Consideration should be given to the volume of water and area of roof space that is being directed into the tank system.

  1. Important: Before starting you must determine final finished ground level to determine excavation size. Tanks must not be more than 100mm above the finished ground level.
  2. Excavate using the minimum excavation depth. Using minimum excavation depth enables the top of the tank to be 100mm above finished ground level.
  3. If joining tanks of different sizes, please plan your excavation accordingly. It is recommended that the Master tank (with pump) be the larger tank.
  1. Backfill excavation with a minimum of 100mm recycled concrete (free of rocks), before placing the tank. A mounded area around the tank to shed the water is preferred.
  2. Before placing the tank into the excavation, check that the fittings have not been damaged during unloading and site handling.
  3. Place the tank on a level 100mm base of 5-7mm Crushed Blue Metal or recycled concrete.
  4. Position the tank in the hole to suit desired site connections.
  5. Multiple tanks – Important: If installing servant tanks, position all tanks with outlets facing the same side wall of the excavation.
  6. Fill the tank with a minimum of 50% water.
  7. Pour a 200mm thick ring of concrete around the (feet) base of the tank.

Materials needed: 5 – 7 mm Crushed Blue Metal or recycled concrete. The use of the specified backfill is important to prevent flotation and minimize soil settlement and the risk of connection failure resulting in water contamination or loss.

  1. Backfill evenly around the tank with recycled concrete or 1 – 6 sand and cement mixture, up to the side of overflow outlet.
  2. Fill the tank to mach the level of the backfill while backfilling.

WARNING: DO NOT DUMP FILL MATERIAL on one side of the tank at any one time or use mechanical compaction or wheel rolling.

  1. Connect rainwater/grey water system fittings and pump.
  1. Top up backfill to finished surface level with topsoil free of rock and stones that is suitable for planting. It is recommended that the tank is installed high enough to create a landscaping mound of a minimum of 100mm or higher so as to prevent any accumulation of water around the top of the tank.