If you relish a pint of Guinness or Stella Artois at your local pub, it’s worth taking a closer look at your glass before you sip. A recent hygiene study conducted by Glass Balustrades UK, in partnership with 15 pubs across the UK and Ireland, has uncovered alarming findings about the cleanliness of pub glasses.
The study involved inspectors visiting 15 different pubs, testing 5 glasses of each popular drink at every location—amounting to 75 glasses per brand. The results were surprising: some drinks, including Guinness and Stella Artois, were significantly more likely to be served in glasses contaminated with bacteria and residue than others.
The 5 Most Unhygienic Drinks in UK and Irish Pubs
After testing 75 glasses of each beverage across 15 pubs, the following drinks were found to have the poorest glass hygiene, with the highest levels of bacteria, residue, and visible contaminants:
- Guinness – 62% of tested glasses contained yeast buildup, biofilm, and lipstick marks, often caused by improper rinsing and the interaction between nitrogen-based beers and glass surfaces.
- Stella Artois – 58% of glasses showed significant bacterial presence, largely due to the specific design of branded glasses which require thorough cleaning but commonly receive only a quick rinse.
- Cask Ales (e.g., Doom Bar, London Pride) – 54% of glasses retained stubborn residue; the lower carbonation in these ales means they don’t naturally help lift grime from the glass surface during pouring.
- Espresso Martinis – 51% of tested glasses contained sugar and dairy residue, which can harbour bacteria if not properly scrubbed after each use.
- Red Wine – 48% of wine glasses exhibited lipstick marks and tannin stains, often the result of inadequate hand washing rather than thorough machine cleaning.
Why These Drinks Are the Worst for Glass Hygiene
The study highlighted that specific characteristics of certain drinks cause them to cling stubbornly to glass surfaces, complicating proper cleaning efforts:
- Guinness and cask ales: Their lower carbonation means they don’t rinse the glass naturally as they are poured.
- Stella Artois and other lagers: Served in specially branded glasses that need intensive scrubbing but are often only given a quick rinse.
- Cocktails with dairy or sugar, such as Espresso Martinis: These leave behind invisible films that trap bacteria if not properly washed.
- Red wine glasses: Often receive only a quick rinse, leaving behind tannins, oils, and bacterial contamination from previous use.
The ‘Quick Rinse’ Problem – Pubs’ Biggest Hygiene Mistake
A significant issue uncovered was the widespread reliance on quick rinsing instead of thorough glasswashing, contributing to contamination risks. Many pubs use outdated glasswashers that fail to reach the recommended sanitization temperatures.
Alarmingly, nearly 50% of the studied pubs had glasswashers operating below 60°C (140°F), well under the Food Standards Agency’s recommended 70°C (158°F) or higher for effective sanitization. This temperature shortfall allows bacteria and yeast to survive and multiply on glasses, even when they appear clean.
How to Spot a Dirty Pint Glass Before You Drink
Before enjoying your pint, experts at Glass Balustrades UK recommend checking for these common warning signs that your glass may be unclean:
- The Bubble Test: A ring of small bubbles clinging to the inside of your pint glass indicates surface residue that prevents proper carbonation release.
- Lipstick or Smudges: Visible marks around the rim are clear evidence the glass hasn’t been thoroughly cleaned.
- Flat or Foamy Beer: If the beer’s head dissipates too quickly or is unusually flat, it could be due to residual grease or detergent interfering with foam retention.
Final Warning from Glass Balustrades UK
“Most pub-goers assume their glasses are spotless, but our study reveals this isn’t always true,” says a Glass Balustrades UK spokesperson. “If you regularly enjoy Guinness, Stella Artois, or cask ales, it’s wise to inspect your glass carefully before each pour.”
Next time you order your favourite drink, take a moment to check your glass. What you don’t see could be more concerning than you imagine.
Frequently Asked Questions (FAQs)
Due to their lower carbonation levels, these drinks don’t naturally rinse the glass during pouring. This allows residue and bacteria to cling to the glass surface more easily.
Glasswashers should reach a minimum temperature of 70°C (158°F) to effectively kill bacteria and yeast on glassware.
Yes, glasses with logos or special designs often require more meticulous cleaning to remove residues that quick rinsing cannot eliminate.
Look for visible signs such as bubbles clinging to the glass, lipstick marks, and check that the beer has a good head that lasts. When in doubt, ask staff if the glass has been properly sanitized.
Yes, red wine glasses can retain tannins and oils that require thorough hand or machine washing to avoid residue buildup.
