Your Water Bottle Is Harbouring 300,000 Infectious Germs, Expert Warns

by : Cameron Frew on : 12 Oct 2019 10:07
Water Bottles ThumbWater Bottles ThumbPexels

As you suckle on the teat of your water bottle, you may be wrapping your mouth round a hotbed of bacteria. 


While your humble bottle may not look grotty, if you’re not giving it the proper care it requires, there could be walls of invisible germs building up inside.

It’s good to reuse them – Americans purchase nearly 50 million water bottles every year, with less than 30 per cent ending up recycled – but it’s important to keep it clean.

Plastic Water BottlePlastic Water BottlePixabay

In an interview with Mashable, Dr Philip Tierno, a clinical professor of pathology and microbiology at NYU Langone Medical Center, explained that just thoroughly rinsing it won’t be enough.


As per Mashable, Dr Tierno said: 

Bacteria tend to form a biofilm on the inside of the reusable container over time. So you need mechanical action to get rid of that biofilm that coats the inside of the bottle.

In order to avoid what Dr Tierno likens to barnacles on a boat, or soap grime on a bathtub, you need to scrub every inch with hot, soapy water and a bottle brush at least once a week.

What is biofilm, though? It’s the makeup of bacteria that was already inside your mouth – known as backwash – and outside materials after drinking while out in about. It’s the latter that poses the greatest threat to your health, according to Dr Tierno.

Dr Tierno gave a harrowing insight into how the germs could spread: 

Some people may [for example] carry strains of staph that other people don’t have. They may pick those up shaking hands with somebody, touching things like countertops, doorknobs, elevator buttons, telephones, computer keyboards.

You’re constantly exchanging flora on your hands, and then you’re touching your water bottle. You’re unscrewing it, capping it, scraping lipstick from the mouthpiece – basically, you’re ensuring that whatever was on your hands is getting into that water.

Treadmill Reviews conducted a study of the number of germs in 12 water bottles – they found ‘that reusable drinking containers may be crawling with an alarming number of viable bacteria cells: more than 300,000 colony-forming units per square centimeter (CFU/sq cm)’.

Plastic Water BottlePlastic Water BottlePixabay

So, when you fail to clean your bottle and welcome the bacteria into your system, ‘you’ve now introduced norovirus into that mixture of flora’.

Dr Tierno explains that this can happen with faecal-borne organisms – the transmission of a disease wherein pathogens in poo particles pass from one person to the mouth of another person – and ‘that’s what you really have to worry about’.

The level of danger varies from bottle to bottle – those with wide, circular mouths pose the smallest threat, but those with rubbers caps (for example, a Lucozade Sport bottle) must be cleaned specifically in line with the product’s instructions.

Try not to worry if you’re not in the habit of cleaning your bottle: it’s not too late to start, just make sure to use plenty of hot, soapy water. Get in about all those nooks and crannies too.

Extreme Contagion vibes… I’m going to be slamming the hand sanitiser all day.

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Cameron Frew

After graduating from Glasgow Caledonian University with an NCTJ and BCTJ-accredited Multimedia Journalism degree, Cameron ventured into the world of print journalism at The National, while also working as a freelance film journalist on the side, becoming an accredited Rotten Tomatoes critic in the process. He's now left his Scottish homelands and took up residence at UNILAD as a journalist.

Topics: Health, Bacteria, plastics, water


Mashable and 2 others
  1. Mashable

    How disgusting is your water bottle, really?

  2. Earth Day Network

    Fact Sheet: Single-Use Plastics

  3. Treadmill Reviews

    A Look Under The Cap: Water Bottle Germs Revealed