Digital Spys Lewis Corner thought the song possessed the "chewiest melody" Adele had ever recorded to, and though its production recalled Kurstin's work on
Katy Perry's album
Prism (2013), Adele distinguished it due to the piercing lyrics and her vocals.
Clashs Gareth James felt that, though it had a behemoth chorus, it perfectly balances between being monumental and innocuous.
Stephen Thomas Erlewine of
AllMusic described "Water Under the Bridge" as "begging to be played over the closing credits of an inspirational biopic". Writing for
Exclaim!, Sarah Murphy was pleased by Adele taking a break from the "piano-pop formula" to explore "more interesting, groove-driven patterns" on the song.
The New York Times wrote that Adele depicts the gravest of pain with a great deal of lucidity and composure on "Water Under the Bridge", and it could be placid if Adele's vocals were less loud. Gerard deemed the song among
25s "least successful tracks", owing to its beats and Adele's extremely loud vocals. He thought its melody resembled pop radio hits of the time but found its concluding "
wall of sound" and choir a "stirring conclusion".
The Timess Will Hodgkinson, and the
Business Posts Johnnie Craig and Tony Clayton-Lea, criticised its 1980s influences, the latter pair describing it as "a forgotten 1980s dad-funk B-side". The song appeared on retrospective rankings of Adele's discography in the 2020s.
Rolling Stone listed "Water Under the Bridge" as Adele's 18th-best song, Brittany Spanos expressing disappointment that "this slice of pop heaven" did not become a huge success.
Billboards Chuck Arnold placed the song at number 28 in a ranking of her discography and noted that though it is "a perfectly good pop song" and "Adele elevates whatever she touches", it could have been recorded by any of her peers.
Alexis Petridis of
The Guardian, who ranked it at number 34, offered a similar take: "'Water Under the Bridge' lays bare the drawbacks of working with blue-chip songwriters, [...] It's a perfectly serviceable bit of pop-soul, with a good chorus and a vague hint of
tropical house, but it feels slightly boilerplate." ==Commercial performance==