A BBC investigation has found that some ice used in the largest UK coffee chains contains bacteria from faeces.
Iced-drink samples were taken from Costa Coffee, Starbucks and Caffè Nero. The samples were found to contain various levels of the bacteria, according to the BBC's Watchdog.
The investigation said at Costa, seven out of 10 samples were found to contain the bacteria, whereas for Starbucks and Caffe Nero, three out of 10 ice samples contained faecal bacteria.
Tony Lewis, of the Chartered Institute of Environmental Health, said: "These should not be present at any level, never mind the significant numbers found."
He also said that the bacteria found are "opportunistic pathogens - the source of human disease."
Watchdog also tested the cleanliness of trays, tables and high chairs at 30 outlets.
Following the investigation, Costa said that it has now updated ice-handling guidelines and will implement new storage for ice.
Starbucks has announced that it will launch its own investigation on the matter as a spokesperson said it takes hygiene "extremely seriously."
A Caffè Nero spokesman said that the company will conduct its own investigation and take "appropriate action".