A mid-tempo pop, soul and soft rock song, "Water Under the Bridge" incorporates influences of 1980s music, R&B, and a gospel choir over guitars and snare drums.

Inspired by her relationship with charity founder Simon Konecki, who Adele dated for seven years and married in 2018, the song speaks of forgiveness and details the crucial point in a courtship of determining whether one's partner is willing to put in the work to make it succeed.

It reached number one in Israel and the top 10 in Poland, Belgium, and Iceland and gained Platinum or higher certifications in Canada, Mexico, and the United Kingdom.

[3] They wrote the song "Hello" (2015),[4] which was released as the lead single from the album and reached number one in 36 countries, and its music video broke the Vevo record for most single-day views.

[7] The latter was inspired by Adele's relationship with charity founder Simon Konecki, whom she dated for seven years and married in May 2018, a topic she is usually reluctant to discuss in her music.

[14][15] Columbia Records serviced "Water Under the Bridge" to adult album alternative and contemporary hit radio stations in the United States on 14 and 15 November 2016, respectively.

After a series of key changes, the gospel choir in the background "finally gets going" towards the climax of "Water Under the Bridge" according to PopMatters's Chris Gerard,[25][26] which Rolling Stone's Jon Dolan described as "gospel-steeped ecstasy".

[24] Cinquemani likened "Water Under the Bridge" to the work of Jessie Ware and found its abstruse but intrepid flourishes among the few moments on 25 that did justice to Adele's strong and dynamic voice.

[28] Writing for DIY, Tom Connick said the clangorous drumming and capering guitar lines elevated the song, and The Telegraph's Neil McCormick described it as a mysterious and booming "big production drama".

[37] 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.

[26] The Chicago Tribune's Greg Kot found the gospel choir a sketchy addition on "Water Under the Bridge" and its snare drums annoying and reminiscent of a cannon being fired.

[40] The Times's Will Hodgkinson, and the Business Post's Johnnie Craig and Tony Clayton-Lea, criticised its 1980s influences, the latter pair describing it as "a forgotten 1980s dad-funk B-side".

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.

[44] 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.

[15][80] In November 2021, a tweet containing a mashup of "Water Under the Bridge" and Megan Thee Stallion's performance of "Body" at the American Music Awards of 2020 went viral.

A dance challenge with the mashup gained popularity on TikTok and users attempted to recreate the clip's choreography, in spite of Adele's apprehensions about the application.