Keith Dunne got Saints back to winning ways with the only goal of a poor game to inflict further misery on sorry Waterford who finished with ten men.
Dunne struck for a cracking winner on 40 minutes when latching onto the return pass from Robbie Doyle to flick a well-placed header past Packie Holden.
Gerard Rowe and Barry Prenderville came close to adding to that lead late on before Blues defender David Breen was shown a straight red card on 85 minutes for an apparent headbutt on Rowe.
