Shirley Bakery employee Kim Evans was on her hands and knees scrubbing silt and mud from the floor when the Prime Minister walked in.
He apologised for treading more mud in.
An exhausted Evans told Key not to worry.
"Don't worry, we've at least four more scrubs to go," she said.
Floodwaters breached the bakery doors yesterday as Christchurch battled a one-in-100-year deluge.
The entire bakery was a mess and needed to be cleaned and sterilised.
Key visited the Shirley shops on the corner of Warrington St and Shirley Rd with Earthquake Recovery Minister Gerry Brownlee, asking them how the cleanup was going, telling them to "hang in there".
Evans told Key they had scrubbed the floor so many times the varnish was starting to come off.
Bakery worker Harmony Evans, 19, said the water had lapped up to a few inches around the store and in the walk-in coolers.
But despite water lapping around their feet, they kept on baking.
"We had orders which had to be filled - we couldn't stop," she said.
Evans said it would be at least another day before they could reopen.
"Three of us have been cleaning since early this morning - it's the worst I have ever seen it. Last year's floods were nothing," she said.
Two doors down Noodle Union owners didn't have time to chat to the Prime Minister.
Their extended family were busy on the end of brooms pushing muddy water and debris from their shop.
Family member Jay Huang said they were trying to get the business open as quickly as possible.
"I'm here helping my brother. We need to open," he said.
Water had seeped into the Mad Butcher to about three inches above the floor level, franchise owner Kyle Vlasveld told Key.
He and employee Daniel Dixon had raced around that morning pushing out water and cleaning the shop.
A young business-owner in Warrington St fears insuring her hair salon is a pipedream after further flooding in her area.
Kimberley Heywood, 26, opened Transform Me a year ago and has been unable to get insurance for her business.
Heywood and Abbey Cox, a hairdresser who rents a chair there, spent the morning sweeping the shop floor.
"We're probably the best-dressed cleaners in Christchurch," said Cox.
Heywood's black boots were covered in mud and Cox wore polka-dot gumboots.
"When we came in this morning, the tide was up to there," said Heywood, holding her hand about 10 centimetres from the floor.
"It was such a mess. It smelled really swampy. I just wanted to cry. No-one is going to want to insure us now."
The tide-mark from Wednesday, however, was even higher.
There were sodden sandbags at the front door.
Heywood and Cox estimate that between them they would have lost about $1000 in two days.
Their phone was "fried - the jack was down in the water", so yesterday they rang all their clients using their cellphones.
"None of them have re-booked."
But they are hoping to get back on their feet by today.
"We'll definitely be open."
Do you feel better off than at this time last year?