Galway ran riot at Wexford Park to stay level on points at the top of the table with Cork City.
Goals from Killian Brouder and a brace from Stephen Walsh had them 3-0 ahead at the break before David Hurley finished off the rout with 20 minutes left.
Cork, top of the table on goal difference, don't play until next Friday.
It was goals galore throughout the division, as Waterford and Cobh shared six. Unfortunately for the visitors - in particular Jack Larkin, who bagged two - it was the Déise men who came out on top on a scoreline of 4-2.
Phoenix Patterson, Tummise Sobowale, Louis Britton and Callum Stringer accounted for the home team's goals.
Treaty United and Bray Wanderers drew two goals apiece while Longford Town's short trip to Athlone Town proved worthwhile, as they nabbed a tidy 2-1 win.