Westmeath extended their unbeaten League run at Ardmore as Kieran Martin's brace fired them to their third straight win.
The visitors made the most of the high winds to lead by 11 at halfway. Martin's second goal wrapped up the points for the promotion chasers.
"With the conditions, to play that well and create so many chances, we're very happy," said Westmeath boss Tom Cribbin. "We're not playing at our best but we're starting to get momentum."
Cribbin is targeting a top two finish after sliding down from the heights of Division 1 in 2014.
"We had a lot of injuries and luckily this year we've been blessed that way," he said. "Our panel is stronger this year."
Waterford slipped three points behind the Lake Men, and promotion is now a distant hope.
Westmeath engineered six first-half goal chances, denied by a series of goal-line blocks before Martin netted on 22 minutes following an end to end move.
Joey Veale registered the Deise's solitary first half point as they trailed 1-9 to 0-1 at the break.
Martin netted a second on 44 minutes. Veale punched in a consolation. Ger Egan lashed a penalty over the bar before Thomas O'Gorman carried the ball over his own line in an attempt to deny Cormac Boyle.
Darren Quinn misjudged Gavin Crotty's wind assisted attempt in the sixth added minute as the ball landed in the Westmeath net.
Scorers - Westmeath: K Martin 2-1, J Heslin 0-6 (4fs), T O'Gorman OG 1-0, P Sharry (3 '45s'), G Egan (1f, 1 pen) 0-3 each.
Waterford: G Crotty 1-2, J Veale 1-1, P Hurney (3fs), D Breathnach 0-3 each, C Murray 0-2.
Westmeath - D Quinn 6; J Gonoud 6, K Maguire 6, F Boyle 6; J Dolan 7, P Holloway 6, M McCallon 6; A Stone 7, G Egan 8; K Reilly 6, P Sharry 7, D Lynch 6; K Martin 8, J Heslin 7, J Egan 6. Subs: N Mulligan 6 for Holloway (24), S Corcoran 6 for F Boyle (H-T), C McCormack for Reilly (62), K Smullen for Martin (63), C Boyle for Lynch (68), S Dempsey for Heslin (75).
Waterford - S Enright 7; S Dalton 5, T O'Gorman 6, T Ó hUallacháin 6; J McGrath 6, S Prendergast 6, R Ó Ceallaigh 6; T Prendergast 5, M Curry 5; F Ó Cuirrín 5, D Breathnach 7, C Murray 6; P Whyte 5, J Veale 7, P Hurney 6. Subs: G Crotty 7 for Dalton (38); F Galvin 5 for S Prendergast (53, BC); J Curry 5 for Ó Cuirrín (58); D Guiry for Whyte (65).
Ref - K Murphy (Cork)