This game exploded into life with three second-half goals in a six-minute action-packed period. Galway's Ollie Neary broke the deadlock on 55 minutes when he scored from 12 yards after Waterford goalkeeper Michael Devine did extremely well to parry Kieran Foley's shot from an Adrian Cregg cross from the right.
Five minutes later, Gareth Gorman put the visitors further ahead when his powerfully-struck free from 35 yards soared into the net.
But almost from the re-start Waterford's Brian Flood floated over a cross to the far post and Gerard Stirling's volley gave goalkeeper Eddie Hickey absolutely no chance.
Two minutes from time Waterford's Barry Wood appeared to have been floored by Michael Quirke just inside the area; but referee Aidan O'Regan waved away appeals for the penalty.
The game ended with an untidy melee involving 14 players and when the dust settled Waterford's David Whittle was red carded.
The first half saw plenty of goalmouth action at both ends; but neither side could apply the killer touch. Daragh Sheridan, Eric Levine and Foley went close for Galway; while Karl Gannon and Alan Kirby almost scored for Waterford. A Galway corner by Gorman struck Robert Griffin; but Dave Smith cleared off the line to prevent an own goal.
WATERFORD UNITED: Devine, Smith, Frost, Flood, Riordan, McGrath, Kirby, Griffin, Markey, Gannon, Stirling. Subs - Whittle for Riordan (64 mins); Wood and Kabia for Markey and Gannon (77 mins).
GALWAY UNITED: Hickey, Watson, Quirke, Foley, Cleary, Neary, Cregg, O'Connor, Gorman, O'Donnell, Levine. Subs - Goldby for O'Donnell (60 mins); O'Connor for Cregg (70 mins). Referee: Aidan O'Regan (Cork).