Picture it.... SeaTac (can't recall the date so insert your favorite one) flying SEA to EWR. GA apologizes to all those waiting with an announcement that goes something like this.

I apologize for the delay. We are experiencing a mechanical problem as the toilet on this plane is inoperable and human waste is backing up into the plane. We have a maintenance crew working as quickly as possible to resolve this issue. (45 minutes later) We appreciate your patience during this delay. If you have not already done so, please use the restroom here at the airport as there will be no rear lavatory for use on this flight. Anything you can do to lessen the number of trips to the forward lavatories during flight will be greatly appreciated. We will begin boarding in about 10 minutes as the maintenance crews finish sealing the toilets.

Sometimes you can share too much. IMHO