Whether you regularly run with a plastic water bottle, or just grab one mid-race, new research will make you stop and think about what's actually in the water you are drinking.
The World Health Organisation has announced it will launch a review into the potential risks of plastic in drinking water after a new study found tiny pieces of plastic in the world's most popular water brands.
It comes after journalism organisation Orb Media tested more than 250 bottles from 11 brands - including Nestle Pure Life, Dasani, Evian, San Pellegrino and Gerolsteiner - across nine countries in Asia, Europe, Africa, and the Americas.
The study, which was conducted at the State University of New York in Fredonia, found that found 93% of all bottles tested contained some sort of microplastic. The researchers also said there was a global average of 10.4 plastic particles per litre.
There is no evidence that microplastics are harmful to human health, but in response to the study, the WHO has told the BBC it will now measure the impact of consuming particles of plastic over a lifetime.
"When we think about the composition of the plastic, whether there might be toxins in it, to what extent they might carry harmful constituents, what actually the particles might do in the body – there's just not the research there to tell us," Bruce Gordon from the WHO said.
"We normally have a 'safe' limit but to have a safe limit, to define that, we need to understand if these things are dangerous, and if they occur in water at concentrations that are dangerous."
Manufacturers contacted during the investigation have insisted that their products meet all government requirements. Two brands, Nestle and Gerolsteiner, confirmed their own testing showed their water contained microplastics, but at much lower levels than what Orb Media is suggesting. None of the other brands agreed to make the results of their tests for plastic contamination public.
Some researchers say there's nothing to worry about when it comes to consuming microplastics in food and water.
"Based on what we know so far about the toxicity of microplastics - and our knowledge is very limited on that - I would say that there is little health concern, as far as we know," Martin Wagner, a toxicologist at the Norwegian University of Science and Technology, said in response to the study.
However, the findings do show how "intimate" our relationship with plastic has become. According to Euromonitor, 1,000,000 plastic water bottles are bought every minute, and less than 50% of these make it to the recycling bin.
"Plastic doesn't need to travel through the oceans and into fish for you to consume it," Wagner added. "You get it right from the supermarket." Just another reason to start taking the plastic waste issue seriously.
BPA-free, reusuable running bottles:
When it comes to running with a reusuable running bottle, you'll need it to be light, not to leak and easy to wash. Here are a few best buys to consider:
If you like running with water to hand, this Ronhill wrist bottle is easy to hold, BPA free and available in two different sizes.
The one-handed bottle opening comes in handy, as does the fact that this bottle is leak-free and dishwasher safe.
The soft flask is designed to compress as you drink, making it lightweight and easy to drink from as you run. It's BPA and PVC free and super light to run with.
Light enough to run with, but big enough to keep you hydrated on a long run, the zipped pouch comes in handy when it comes to carrying those extra essentials. The insulated bottle will keep your water cold and the HydroGuard polypropylene will stop that horrible bottle taste after a few washes.
This soft, foldable bottle is a great option for long runs. Keeping your water cold for twice as long, without the weight, the self-sealing bite valve means there's no risk of spilling water as you go.
A version of this article appeared on Country Living.