In an extreme rainfall event there is the possiblity that water can back up through the stormwater overflow pipe and towards the rainwater tank.
If your local stormwater infrastructure (beyond your property boundary) becomes blocked, the system can “charge”, causing dirty stormwater to surge back through your stormwater pipework. If your rainwater tank overflow is connected to stormwater, this “charged” stormwater can backup into the tank.
If the pipes connected to the overflow of the rainwater tank are crushed, excess water from any pipework connected to the same system could flow back towards the tank, taking with them whatever debris is in the system.
If your tank is going to a soakage pit, in an extreme rain event the pit could become saturated and water can flow back up towards the
An air gap prevents this problem by creating a physical gap between your rainwater tank and stormwater lines. With an air gap, overflowing stormwater is prevented from backing up into your tank. Instead, it will spill out through the front of your air gap.
Check that the bayonet fitting is engaged correctly. Push and turn the top filter to secure the screen in place.
You can install your air gap at the top or bottom of the vertical overflow pipe. Installing your air gap closer to the top of the overflow will generally make it easier to maintain.
We recommend ensuring you don’t have a charged line which could effect the height of installation.
You can connect the downstream (bottom) side of your air gap to a 100mm pipe with the use of a 100×90 socket reducer. Please consult a licenced plumber for suitability in reducing the upstream (top) connection to your air gap.
Overflowing rainwater from your tank can begin leaking from the air gap if the bottom screen becomes dirty or obstructed. To prevent this problem, regularly check and clean your bottom screen.