Regan swam a time of 23.38 and was sixth in heat nine of the 50-meter freestyle. There were 12 heats in wave I of the Olympic Trials.
He qualified for the USA Swimming Olympic Trials with a time of 22.98 at the 2021 Greater Philadelphia Aquatic Club Spring Derby on May 22. The qualifying time for the wave I cut was 23.19. USA Swimming split the meet into two waves because of Covid restrictions. The first wave was June 4-7 and the second wave is scheduled for June 13-20, which features faster standards and will serve as the main selection meet.
In 2020, Regan was a member of the All-America Team on the 200 and 400-yard medley relays and the 200-yard freestyle relay. He was named to the NJAC All-Conference first team in the 100-yard freestyle and the second team in the 50-yard freestyle. Regan was chosen to the All-Conference first team 200 and 400-yard medley relays and 200-yard freestyle relay. He received NJAC second-team honors as part of the 400-yard freestyle relay.
Regan took second place in the 50 (20.41) and 100 (45.79) yard freestyles at the Metropolitan Championships. His time in the 50 yard free was an NCAA B cut. He swam on the first-place 400-yard medley relay (3:16.15) and second-place 200-yard medley relay (1:29.03) and second-place 200-yard free relay (1:20.81) that had school record and NCAA B cut times at Mets.
Regan was also on the second-place 400-yard freestyle relay (3:05.60). A Rowan Scholar-Athlete, he had a season-best time of 45.74 in the 100-yard freestyle and 1:45.10 in the 200-yard freestyle.