Cushla Virtue put $40 of fuel into her Suzuki Swift on Wednesday morning last week, but barely made it home after the engine started to fail.
Now she is working to get BP to pay the bill for her repairs after water was found in the fuel tank.
She said the car was running "perfectly fine" until she filled up at BP Connect Bays Junction in Andersons Bay Rd.
While heading up a hill on the way home the car started misfiring and shaking "terribly" and the engine warning light came on.
"I barely made it up the hill."
"I was beside myself," she said.
As a final check, the mechanic decided to drain the tank and try running it with a different fuel.
The car then ran totally fine, she said.
They poured her a glass with the drained fuel, which was about two-thirds water.
The bill came to $466, which she had sent to BP, along with a bank statement and a letter from the mechanic.
BP had responded, saying it was reviewing the evidence, she said.
She understood mistakes could happen, but had not seen any statement from BP warning other customers that might be affected.
The mechanic she used said she was lucky to be driving an earlier model of car.
Water in the fuel could be a far bigger issue in later-model cars and could cost $500-$5000.
"It can really stuff an engine," the mechanic said.
He had heard of about 10 other people who had been affected by the issue.
A BP spokesman said it had identified an issue affecting the supply of regular 91 grade fuel from four of pumps at BP Connect Bays Junction on Wednesday morning last week.
It was investigating the pumps following reports of water in the fuel and they remained unavailable for use.
BP was working with affected customers to resolve the issue, he said.
