Plummer pursued higher education in Language Studies at the University of Minnesota. His academic background is complemented by his fluency in English. His family includes his wife Erin and their two sons, Will and Ricky.

| Season | Event | Rank |
|---|---|---|
| 2016 | Men's 4 x 100m Medley Relay | G Gold |
| 2016 | Men's 100m Backstroke | B Bronze |
One of Plummer's most memorable sporting achievements is winning bronze in the 100m backstroke at the 2016 Olympics. This accomplishment made him the oldest first-time US Olympic swimmer since 1904. He was 30 years old at the time.
In January 2017, Plummer announced his retirement from competitive swimming. He had made this decision after the 2016 Olympics. Plummer stated, "I haven't been in the water since Rio, so this has been true for a while, but now I am saying it out loud and I am admitting it to myself. I am retiring."
Post-retirement, Plummer has been involved in coaching. He has coached the junior swim team at Wayzata High School in Plymouth, MN.
In August 2016, Plummer was selected to sound the Gjallarhorn for the first match at the new stadium of the Minnesota Vikings. This honour is similar to throwing out the first pitch in baseball.
Outside of swimming, Plummer enjoys listening to music, reading, playing with his dog, and cycling. These hobbies provide a balance to his athletic career and coaching responsibilities.
Plummer's brother Ryan was an All-American swimmer between 2000 and 2004 at the University of Minnesota. This family connection highlights a strong swimming tradition.
Plummer's sporting philosophy is encapsulated in his motto: "True strength is the ability to weather a storm." This mindset has undoubtedly contributed to his resilience and success in swimming.
David Plummer's journey from a young swimmer to an Olympic medallist and coach is inspiring. His achievements and contributions to swimming continue to be recognised and celebrated.Plummer pursued higher education in Language Studies at the University of Minnesota. His academic background is complemented by his fluency in English. His family includes his wife Erin and their two sons, Will and Ricky.