Potter, 29, who competed at the 2016 Olympics, clocked a time of 14 minutes 41 seconds on Saturday.
That beat both Paula Radcliffe’s 14:51 British record, and Kenyan Beatrice Chepkeoch’s world-record time of 14:53.
The event will now be examined to see if it meets licence and drug-testing requirements to qualify for an official record, with the 29-year-old athlete in excellent form ahead of the rearranged 2020 Tokyo Olympics.
“It was really good to get a race in the early season but that was beyond my expectations,” Potter told BBC Radio 5 Live.
“It all started to sink in when I had about a kilometre to go and I saw the clock said 11 something and I was trying to do the maths in my head.
“I was convinced the clock was wrong.
“I couldn’t believe it.”
After making the move to triathlon four years ago, Potter said she hoped to be competing at the 2020 Tokyo Olympics but she missed out on selection.
“It’s frustrating because I feel like I’m an in-form athlete at the moment,” she said.
Potter finished 34th for Great Britain in the 10,000m at the Rio 2016 Olympics before switching to triathlon, winning gold at the 2019 European Championships.