Shopkeepers were forced to clean away raw sewage with their hands to protect their businesses after a drain flooded.
Businesses and traffic in West Croydon ground to halt on Friday afternoon after waste water spewed out of drains in London Road and seeped into nearby properties.
The road was shut off between Hathaway Road and Sumner Road while engineers worked to clear a blockage, thought to be caused by fat flushed down the drains of nearby takeways.
Staff described having to wade through sewage to salvage their businesses after it leaked in at their front and back doors.
Joy Bowling, who runs Halos hair and beauty salon, said: "The water was flowing through the street and then it started to come in through the drain at the back and through the kitchen door.
"We spent two hours clearing it away. I had to wade through poo in my shop and pick up lumps of it with my hands. The stench was awful."
Parvez Iqbal, 45, who owns food shop Ambala, said: "We have lost stock as a result of this. We have got a storage area at the back that has suffered damage."
He said the flooding was "the icing on the cake" for London Road businesses, who suffered badly in last year's riots.
Mr Iqbal said: "We are already suffering and now this. It is just one thing after another. There is always a problem.
"They should have have seen this coming - the drainage system has not worked properly since the big fire in the riots. But they don't really pay attention until there is a disaster."
Ms Bowling added: "I dare not claim on my insurance for this because it is still sky high after the riots. We don't know what to do any more."
A spokeswoman for Thames Water described the internal sewer flooding as "utterly horrific", adding: "We are doing everything we can to help these people. We're really sorry for the mess this has caused."