“The requirement for fall in the piping means that conventional gravity systems are typically located either subterranean or in the slab” and are subsequently “set in concrete”. Changing the location of the piping or adding fixtures is extremely costly and difficult to achieve. Avac Australia Vacuum drainage systems on the other hand-are extremely versatile; they can be routed to run uphill, around site constraints and fixtures can be easily moved, added or removed at any time with minimal cost and disruption.