The game looked like it may have been heading for a scoreless draw until Willie John Kiely popped up in the 77th minute to grab all three points for the home side.
The result means that James Gallagher’s side are still without a win this season despite playing an attractive brand of football.
The home side had most of the play but found it difficult to find a way through the Harps defence, but when they did, Ciaran Gallagher was in a good form to deny them.
The game started very slowly with neither side taking control of the game but Kevin McHugh almost got on the end of Gary Whoriskey free-kick.
The home side should have taken the lead after 13 minutes when Kiely chested through ball to Conor Sinnott to put the midfielder through on goal but Ciaran Gallagher came out well to save.
Again the home side threatened two minutes later but Kiely couldn’t connect with Gary Dunphy’s cross. Kevin McHugh had Harps first strike on target, but Kevin Burns saved easily.
Gallagher was called into action again soon but he got down well to save Conor Sinnott’s low drive from the edge of the box. The resulting corner saw Kenny Browne’s header cleared off the line.
Minutes later Gallagher again saved Harps as he touched over a header from Waterford centre-back Kevin Murray. The home side were in control but unable to find the back of the net as Harps continued to defend well.
The second half began with Finn Harps on the attack. Kevin Burns saved the initial attempt but Kevin McHugh blazed the rebound over the crossbar from 5 yards. Sinnott headed over the crossbar shortly afterwards before Seamus Long and Shane Barrett also went close.
The only goal of the game arrived 13 minutes from the end. Gary Dunphy played in Gary Keane just inside the right of the Finn Harps penalty box, and his low shot was parried by Gallagher to the inrushing Willie John Kiely who fired into the roof of the net. Finn Harps had defender well in numbers throughout the game but came undone.
The game completely fizzed out from this point as the home side were happy with the one goal advantage, but the away side tried in vain to get back into the game.
Waterford United: Kevin Burns; Seamus Long, Kevin Murray, Kenny Browne, Michael Coady; Gary Dunphy (Dwayne Wilson 91), Conor Sinnott, Shane Barrett, Gary Keane; Keith Quinn (Shane Dempsey 88), Willie John Kiely.
Subs not used: Josh Byrne, Lee Chin, Paul Carey, Brian Nolan, Michael Rafter.
Finn Harps: Ciaran Gallagher, James Doherty, Packie Mailey, Keith Cowan, Ciaran Coll; Gareth Harkin, Oisin McMenamin (Gary Merritt 78), Paddy McLaughlin (Raymond Foy 29), Conor O’Grady, Gary Whoriskey; Kevin McHugh.
Subs not used: Lee McFadden, Aaron O’Hagan