Originally Posted by rickg523

I didn't think the OP was expecting a dissertation.
I didn't think the issue was the operational constraints of the toilet flushing system on the Airbus.
I think the reason the OP posted was because he felt he was being treated like a child. "Oh, honey, don't fret, it's like that on all the airplanes."
I also agree with an earlier poster that the crew infantalized their response to a simple question because they are under no delusion that if they offhandedly admit an equipment failure and as a result some passenger makes a compensation claim (almost a certainty in 2018), it'll be their butt in a sling with their supervisor.
In the end, though, it was interesting to learn how these things operate. But I personally prefer to avoid airplane lavs if possible and always use the terminal facilities before boarding.