Reduce, re-use, re-volting

Most of us are guilty of ignoring that questionable layer of grot building up inside our water bottles. Katie Rosseinsky looks at the consequences of failing to clean them properly

- Katie Rosseinsky

Here's an unexpectedly confronting question: when did you last clean out your reusable water bottle? You know, the one that you've been toting around with you from the train to the office to the gym ad infinitum. The one that's developed a suspicious layer of grot around the lid that you're trying not to think about.

That you accidentally left festering in the car on a swelteringly hot day. And when I say clean, I'm not just talking about a cursory slosh of fresh water and a bit of damage control around the neck - I mean a proper scrub, or at least a go-around in the dishwasher.

If we're being entirely, unflinchingly honest, the answer for most of us is probably something along the lines of "I've left it a little bit longer than I should have." It's all too easy to just throw your bottle in your bag before racing out the door, and make cleaning it a problem for tomorrow. Or the day after. But the stomach-churning truth is that our trusty vessels are actually harbouring quite a staggering amount of bacteria, often without us even realising it.

In 2023, researchers from the US company Water Filter Guru swabbed reusable bottles and found that the average one was 40,000 times dirtier than a toilet seat. It's enough to put you off your recommended two litres per day.

Over the past decade or so, we've gradually become more aware of exactly what our (disposable) bottled water habit has been doing to the environment. The average single-use plastic bottle can take around 450 years to break down in landfill, shedding tiny particles known as microplastics as it decomposes. These build up in the soil and in the oceans, accumulating in the food chain and eventually cropping up in the stuff we eat; they've also been linked to a whole range of health problems, including hormone disruption and various cancers.