Thinking of getting a refreshing iced coffee from Starbucks to beat the heat?

SEE ALSO: Kelly Osbourne peed her pants and is blaming Starbucks

Think twice after reading this.

A BBC Watchdog investigation uncovered significant traces of faecal bacteria in ice from three of UK's high street chains — Costa Coffee, Starbucks, and Caffe Nero.

In other words, there's poop in your "Freshly brewed Starbucks® Iced Coffee Blend served chilled and lightly sweetened over ice."

Experts swabbed tables, trays, and high chairs in 30 branches as well as collecting samples of the ice used in their drinks.

Faecal coliforms are bacteria which contain "opportunistic pathogens — the source of human disease," according to expert Tony Lewis. They were found in 3 of 10 samples tested at both Starbucks and Caffe Nero.

In Costa, 7 out of 10 samples contained poop bacteria.

"The level of contamination of faecal bacteria concerns me a great deal," Lewis, of the Chartered Institute of Environmental Health, said. "The bacteria found are opportunistic pathogens — the source of human disease. These should not be present at any level — never mind the significant numbers found."

People reacted with shock and irony:

I always knew they weren't cinnamon sprinkles... Starbucks and Caffè Nero pic.twitter.com/xvHdc4kcgZ — Boo Brown (@babyboogaloo) June 28, 2017

For an overpriced, calorific, dirty-iced coffee, Costa, Starbucks and Caffè Nero are the cream of the crap.#walkonby — Lynne (@blonde008) June 28, 2017

Starbucks and Caffè Nero. The only bit of good news for Starbucks is that they can market a new drink the "iced crappuccino" 😜. — Chris Pritchard (@Loper45653919) June 28, 2017

"Starbucks and Caffe Nero" On my way to Costa, views trending... pic.twitter.com/mXfzQ6cMCC — AnSi (@AnethaSi) June 28, 2017

Next time you go into Starbucks and Caffe Nero you can say their coffee's shit knowing you're simply stating a fact. — Dan Patterson (@DanPattersons) June 28, 2017

Really wish I hadn't looked at why Starbucks and Caffe Nero are trending. pic.twitter.com/o8jR1Yb99T — Rachel Hawkins (@ourrachblogs) June 28, 2017

"Starbucks and Caffe Nero" is trending... that should cheer me up on a rough morning... let's click... ... 🤢 — click and hope (@clickandhope) June 28, 2017

People in Starbucks and Caffe Nero this morning checking the trending topics over a nice crappucino pic.twitter.com/oIvVw48qys — Jamrock (@JamrockOne) June 28, 2017

ill take a rain check from starbucks and caffe nero .. pic.twitter.com/wdl8Ye2TrL — lee (@Lee_k100) June 28, 2017

I've suspected for a long time that coffee chains have been following the Baldrick recipe: https://t.co/gsVDmV8ScF https://t.co/x6fJ1es1Tn — Will (@grid212) June 28, 2017

All three coffee chains said they've taken action:

Starbucks:

We want to reassure our customers that we take hygiene and cleanliness extremely seriously. We have moved quickly to conduct our own investigation into the claims. All employees nationwide have received updated training on our high standards of hygiene including ice handling. Nothing is more important to us than the safety of our customers.

Costa:

We were disappointed with the findings, especially as these stores are all rated Very Good with the top Hygiene Rating of 5. 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. Following these results we took immediate action to review our food safety procedures and have updated our ice handling guidelines and are in the process of introducing new ice equipment storage across our estate.

Caffe Nero:

We are concerned to read the findings in your recent report and a thorough investigation is now underway and the appropriate action will be taken.

Watchdog will air on Wednesday, June 28, at 8 p.m. on BBC One.