Polytank PolyA30 is designed to give two levels of protection to stored water systems:

A1 - Type "AB" Air Gap with weir overflow to protect the incoming mains water supply for a Category 5 designated risk of contamination
A2 - Drinking water supply to the water stored in the system. Providing no additives are added into the cistern and no contamnation is caused by any process downstream

Protection A2 noted above CANNOT be maintained if any type of pump is installed downstream of the cistern or if any equipment which may cause backflow is installed downstream.
Protection A2 noted above CAN ONLT be mainteained if the system is a gravity fed system.

The "A"Type Air Gap protection remains valid even if conditions for protection A2 noted above cannot be made.