"Yep, I'm happy now but I was embarrassed by the half-time scoreline," coach Phil Keinzley said after the final whistle.
"Silly errors cost us three soft goals. We'd gone away from the game plan after playing good football for the first 25 minutes."
The 3-1 half-time deficit was wiped out within five minutes of the restart and, from there on, Wairarapa dominated the game completely with what Keinzley described as "the best football I've seen us play".
For United, Seule Soromon netted a hat-trick while man of the match Adam Cowan scored twice and Nathan Cooksley and Paul Ryder also found the back of the net.
The victory extended United's unbeaten run to 11 games, having gone undefeated since the end of last season's Chatham Cup run.