An undercover investigation has revealed that ice and soda water served at a number of leading food and drink chains in the UK are contaminated with faecal bacteria.

The BBC’s Watchdog Live programme sent investigators into 10 different branches each of JD Wetherspoon, Harvester, Slug and Lettuce, Hungry Horse and Marston’s Two for One, totalling 50 visits.

The undercover team collected samples that found bacteria levels were reportedly ‘too high to count’ at all five chains. Among the bacteria, coliforms, including faecal coliforms – which are usually found in the gut and associated with faeces – were present in samples of either ice or soda at each of the chains investigated.

The news comes less than 18 months after Watchdog Live found traces of faecal bacteria in the ice at high street coffee shops including Starbucks, Caffè Nero and Costa.

The findings indicate that such high concentrations of bacteria and presence of coliforms are the result of failings in cleaning standards, and may present a risk to health, particularly those with weakened immune systems.

All of the named chains have responded with shock and surprise to the findings, promising internal investigations and reiterating the importance of cleanliness and hygiene, promising to take on board the findings.