1
general::
Phrase(s): turn on the waterworks
Fig. to begin to cry. • Every time Billy got homesick, he turned on the waterworks. • Sally hurt her knee and turned on the waterworks for about twenty minutes.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Start to weep, as in Whenever Dad refuses a request of hers she turns on the waterworks. This term implies that one begins to weep deliberately, as though switching on a system of pipes connected to reservoirs.
American Heritage Idioms