Water said to be from a sacred Muslim well has been taken off shop shelves, for containing high levels of arsenic.
The water was for sale at a convenience store in Westminster
A complaint was made that bottles said to be Natural Zam Zam Water were on sale in central London. It should only be sold in Saudi Arabia.
Analysis showed the water had high levels of nitrate and three times the permitted levels of arsenic.
No other shops were found selling the product, but Westminster Council's investigation led to a national recall.
Trading standards officers in Barnsley, South Yorkshire, have also received complaints from Muslims about the product being sold.
Results 'a shock'
The investigation in Westminster began with a complaint that the water was being sold in London.
But the results of a sample sent to the public analyst came as a shock, a council spokesman said.
The Food Standards Agency (FSA) said the arsenic "could contribute to increasing people's risk of cancer".
There have not been any reports of anyone being taken ill after drinking the water, and no other samples were found for sale.
Council staff also contacted the importers to stop them bringing more of the water in.
The FSA has warned shoppers to be alert and report any incidences of Zam Zam water for sale to their local authority - particularly as demand increases during Ramadan.
"This advice does not relate to the genuine Zam Zam water being brought into UK by returning pilgrims... as a personal import," a spokesman said.
"As genuine Zam Zam water cannot be legally exported from Saudi Arabia for commercial sale, any product found in the shops would have an uncertain provenance and pose a possible safety risk."