PSA: Yes, You Need to Wash That Disgusting Water Glass

If you don't, you're probably drinking faeces.


I just discovered I might have been drinking faeces the past few years, and my world has never felt like more of a lie.

For pretty much my entire adulthood, I’ve operated under the belief that you almost never need to clean a water glass. Currently, I have exactly two glasses I use on a regular basis — one I keep on my bedside table, another I use for all other areas of my “cozy” one-bedroom apartment. I exclusively drink water out of these glasses, and often I go weeks, if not months, between cleaning them. In fact, I usually don’t clean these glasses until they’re so cloudy with lip marks and fingerprints that you can hardly see through them. Gross!

And yet, I’m able to rationalise this practice because nothing but water touches these glasses. Plus, the filtered water is clean; therefore, the glass is clean.

So why bother cleaning them? I see no flaw in this logic.

That is, until I talked to Kelly Reynolds, a public health professor at the University of Arizona and an expert in water and food safety. She informs me that I’ve been putting myself at risk of ingesting poop by going so long between cleanings. “You said a key word there: Fingerprints on the glass,” Reynolds tells me by phone. The problem with not cleaning your House Glass is that humans are filthy beasts with grubby paws (my words, not Reynolds’). “Any time you touch that glass, you’re building the chance of contamination on that surface, just based on the frequency of your hands touching that glass over time. And then, when, you put your lips to it, you have direct contact with a possible contaminate.”

Some of the potential contaminants include salmonella, hepatitis, norovirus (a common cause of the stomach flu in adults) and rotavirus (which causes diarrhoea in children).

We get this bacteria on our hands merely by existing, because apparently there’s poop on just about everything we encounter in life. Case in point: Trace elements of faecal matter are frequently found on shopping carts and playground equipment, according to Reynolds’ research. People often get this poop on their hands by defecating, wiping and not washing their hands properly. You can also get poop-y hands just by being near a toilet as flushing it can release bacteria within a six-foot radius. And that bacteria can get on your hands, then your glass and then your mouth.

Similarly, bacteria accumulates when you leave out a glass of water overnight. “You may have noticed that the taste of the water changes. That’s bacterial growth,” she says. Studies have even found bacterial growth in sealed bottles of water. These bacteria are mostly harmless, but still, it exhibits how a dirty glass can quickly become a teeming mass of disgusting microbes.

The risk of contamination is higher for refillable water bottles, especially if they have a spout you have to open and close, putting it in direct contact with your disgusting hands. “That’s why most of the spouts on these water bottles are black; they don’t want you to see the mould growing in those crevices,” she says.

That said, Reynolds isn’t too alarmist about this poop. “We just pick up [these bacteria], it’s part of life.” She adds that this is all a matter of risk. Drinking from a used water glass doesn’t automatically result in a bout of the flu. The glass has to be contaminated, and the better your cleanliness habits, the lower your risk of a contaminated glass. So she recommends cleaning your water glass or refillable water bottle every day — sometimes even with bleach.

“I’m big about not being a germaphobe,” she says. “But if you’re doing the dishes anyway, you can give your water bottle and water glass a quick dip, and there you go, it’s clean. It’s no different than telling people to regularly wash their hands.”