Costa, Starbucks and Caffè Nerohave pledged to take action following a BBC Watchdog investigation found that their ice contained bacteria from faeces.

An undercover investigation from the BBC revealed that iced water obtained from the coffee chain trio contained faecal coliform bacteria.

BBC Watchdog found seven out of 10 samples of Costa ice were found to be contaminated with bacteria found in faeces, while both Starbucks and Caffè Nerohad three out of 10 samples test positive for faecal coliform.

Costa told British Baker that they have taken immediate action to update its ice handling procedures.

“We were disappointed with the findings, especially as these stores are all rated Very Good with the top Hygiene Rating of Five,” said Costa in a statement. “It is extremely important to us that all our stores operate to high standards of hygiene at all times and we take it very seriously when any store fails to meet these standards.”

“We adopt industry standard cleaning processes across all our stores, in line with the Food Standard Agency’s advice.”

Meanwhile Starbucks said that it wanted to reassure customers that it takes hygiene and cleanliness extremely seriously and will give updated training of ice handling to members of staff.

Caffè Nerotold British Baker that a thorough investigation was now underway and the appropriate action would be taken.

Hoshizaki, who are the world’s largest manufacturer of commercial ice making equipment, told British Baker that poorly made, inappropriately stored or incorrectly handled ice could become a source of food poisoning.

“The most common form of ice contamination occurs after the ice has been manufactured,” said Lena Palmer, marketing for Hoshizaki. “Dirty, unsanitised ice scoops or rarely cleaned ice buckets leave much to be desired. Few of us would opt to eat food that has been through a poor handling process, and the same is relevant for ice.”

“The only potential sources of danger at the ice manufacturing stage are water and air. It is therefore imperative to protect against the harmful effects of both. The placement of an ice maker is vital – too often they are slotted into any available space, such as damp cellars or unventilated areas, where air quality is at its poorest and aero bacteria are most profound.”

The ice equipment manufacturer revealed that the most important factor to prevent bacteria growth for baristas is regular machine maintenance and personal hygiene.