Ollie Horgan hailed his Finn Harps heroes after they struck late to move off the bottom of the table.
Goals by substitutes Alexander Kolger and Adrian Delap in the last four minutes stunned Waterford, who had led twice at the RSC.
Harps last won on the opening night back of the campaign in February, losing their last six in the league either side of lockdown.
“Maybe we got the luck today that deceived us in recent weeks,” said Horgan.
“Our lads don’t give up and we’ll need plenty more of that for the remainder of the campaign to avoid relegation.”
Waterford shaded a dull first-half, with Ali Coote’s 13th-minute deflected shot from 20 yards handing them a deserved lead.
Their second half struggle to threaten Mark McGinley’s goal gave Harps renewed belief and the equaliser arrived with nine minutes left.
Goalkeeper Tadhg Ryan was all at sea in allowing Barry Mcnamee’s corner kick drift to the back post where Dave Webster prodded home.
Waterford regained the lead two minutes later after sub John Martin beat McGinley with a low drive.
But Kolger headed a second equaliser on 86 minutes before fellow substitute Delap pinched the the points.
