Eric Molloy scored for the second match running as Waterford won this Premier Division basement battle at Bishopsgate to move four points clear of bottom side Longford who finished with ten men.
It's a second win in six games in charge for new Blues' boss Marc Bircham who expects to strengthen his squad in the July transfer window.
Despite producing plenty of spirit and endeavour, Longford's woes continue as Daire Doyle’s midlanders are now without a win in 16 games since the opening night of the season.
If Longford started well, Waterford looked the more dangerous side as they knocked the ball around confidently, probing for openings.
Blues striker Prince Mutswunguma might have made more of a half chance on 12 minutes but completely miscued a Jamie Mascoll corner.
A surging run from Adam O’Reilly then saw Longford having to defend as the midfielder’s shot was deflected into the side netting.
But Waterford would get their reward for a period of dominance as they took the lead on 16 minutes.
Winger Molloy skipped by a couple of tackles on the right to feed O’Reilly’s whose cross was met by John Martin with a diving header Longford goalkeeper Lee Steacy will be annoyed he didn’t prevent from entering the net.
Longford responded well, clinically punishing a Waterford mistake to level within two minutes.
Waterford right-back Darragh Power’s loose diagonal ball went straight to Town’s Aaron McNally who showed clever feet to dribble by Jack Stafford and Kyle Ferguson before finding the bottom corner with a low drive.
Brim full of confidence, McNally was inches from putting Town ahead inside a further minute.
Dylan Grimes and Rob Manley worked the ball to the winger who cut inside to thump a shot that came back off Brian Murphy’s crossbar.
Regaining their composure, Waterford regained the upper hand, enjoying a good bout of possession as half-time approached.
Ferguson had a sight of goal when Molloy found him in a pocket of space in the box, but his header was straight at Steacy.
Waterford remained the better side into the second half and availed of further poor defending to regain their lead on 48 minutes for what would prove the winner.
McNally was rather harshly adjudged to have handled a bouncing ball.
But further ire was to come as Longford failed to clear Mascoll’s free kick which bounced through for Molloy who scored with a sweeping half volley.
Despite chasing the game hard, Longford laboured to breach the Waterford defence.
Manley did get in behind just before the hour mark, but a determined Ferguson got back well to block the Town striker’s shot.
The game was up for Longford on 84 minutes when central defender Mick McDonnell was shown a straight red card for appearing to stamp on O’Reilly.
Longford Town: Lee Steacy; Karl Chambers, Mick McDonnell, Aaron O’Driscoll, Paddy Kirk; Aodh Dervin, Dean Zambra (Aaron Dobbs 73); Aaron McNally, Dylan Grimes, Dean Byrne (Conor Davis 54); Rob Manley (Aaron McCabe 80).
Waterford: Brian Murphy; Darragh Power, Kyle Ferguson, Jack Stafford, Jamie Mascoll; Eric Molloy, Shane Griffin, Niall O’Keeffe, Adam O’Reilly (Callum Stringer 90+2); John Martin, Prince Mutswunguma (Cian Kavanagh 89).
Referee: Ray Matthew (Midlands)