Green’s Dictionary of Slang

a dread or horror of water; thus in general, madness.

1831		R. Ryan Everybody’s Husband I i: This lady’s got the phoby! I’ll be off.
1843–44		Dickens Martin Chuzzlewit (1995) 295: A jug and ewer, that might have been mistaken for a milk-pot and slop-basin [...] ‘They’ve certainly got a touch of the ’phoby, sir.’.