The ten A320 that BA inherited from BCAL, A320-111 and A320-211, have normal gravity toilets like B737-2/3/4/5 B757 DC9 etc. The fwd toilet had a drain on the left hand side under the L1 door. Terrible location because the truck can't reach it under the jetty and it gets missed.
Anyway every other A320 I have worked on has vacuum toilets with a single service point at the rear.
Why do new build A320 still have the fwd service panel fitted, which is blanked off? Can you still order an A320 with gravity toilets?, or is it a design change to remove the panel which would cost too much?