We all use water bottles on a relatively consistent basis, whether we want to or not. They are everywhere — at the market, in fast food establishments, and in our cupboards. Often, in the name of environmentalism, we opt to re-use our water bottles, even if they are of the disposable variety.
The question is, can re-using our water bottles in this way be negatively affecting our health? In some cases, the answer is yes. There are three crucial things that you should know about before refilling your empty bottle with some good old H2O, so hang on to your Brita filters — let’s jump right in.
1. Bacteria can thrive in water bottles.
While you should be OK if you use a disposable water bottle only once (as is intended), you are pushing your luck if you decide to use it again. Indeed,studies have shown that with prolonged usage, disposable bottles acquire scratches and cracks that can harbor nasty types of bacteria. It is not unlike your cutting board, which must be cleaned very thoroughly in order to ensure that all of the bacteria hiding in its gouges are eliminated.
Cleaning out your disposable water bottles cuts down on some of the risk, especially if you use warm soapy water. Still, even that presents a problem, as cleaning those kinds of bottles might damage them further (since they were not designed with re-usability in mind).
It is also important to remember that the bacteria inside of your water bottles gets there via your mouth. So if you do not wash them out, days and days worth of bacteria collects inside of them, turning your bottle into something not unlike a laboratory petri dish. One study from the University of Calgary found that a group of elementary student’s water bottles — which had been re-used several times over without being washed — contained levels of bacteria that went far above what is recommended to be present in your drinking water. This in part had to do with the fact that these bottles sat in room temperature for most of the day, which gave the bacteria present within the bottles the perfect conditions necessary to grow and multiply.
Even specialized re-usable water bottles, such as those made by Nalgene and other companies, aren’t entirely safe. They too can acquire scratches that harbor bacteria, and will become just as contaminated with microbial life as disposable water bottles if they aren’t cared for properly.
Your best defense against bacteria would be to use disposable water bottles only once, since they are exceedingly difficult to clean thanks to their narrow mouths. If you use a re-usable bottle, try and get one that is wide-mouthed so that you can more easily clean its insides, and be sure to give it a good wash every day if possible. And lastly, make sure to wash your hands on a regular basis, as all of the bacteria present on them will most definitely come into contact with your bottle at some point.
2. Cleaning water bottles may lead to chemical leakage.
I stated above that you should use warm water and soap when washing your bottles for a reason — using scalding or boiling water to sterilize your bottle is not recommended. Especially if you are re-using a disposable bottle. One professor stated that cleaning your disposable bottles with boiling water (or in the dishwasher) is a recipe for disaster, as the plastic used in them was not designed to be heated in that manner. When it is, there is a chance that dangerous chemicals might seep out of the plastic and leech into whatever liquids you put into them.
Re-usable plastic bottles are made with a hardier variety of plastic, and should be able to stand up to boiling water better than your standard disposable bottle. That said, there is no way to completely remove all risk when using plastic products. The best defense against chemicals leakage in your drinking water is to use glass or stainless steel bottles, which may be more expensive. Even then, you need to ensure that you wash and dry them sufficiently, lest they fall prey to the bacterial issues I talked about above.
3. Most of a water bottle’s bacteria exists where you put your mouth.
So I have told you that water bottles provide bacteria with a near-perfect ecosystem, and have informed you about how you also have to be careful in regard to how you wash your bottles. But what you probably want to know is “what part of the bottle poses to greatest risk to me?” The answer is: the part where you put your mouth.
Not only is that because your mouth contains bacteria, which then transfers to the bottle, but it’s also because the ridges meant to align with those screw-on caps are the perfect breeding area for microbes. Sure, they can live in the tiny scratches inside of disposable bottles, but their main habitat, so to speak, will be right at the top.
Indeed, one study highlighted this fact. They asked a group of brave test subjects to re-use the same water bottle over the course of a week, and were instructed to not wash them. At the end of the week, scientists took a swab and brushed it against the ridged neck portion of the bottles (basically, the part that goes in your mouth). What they found was disturbing, to say the least. When they cultured the bacteria picked up with the swab, they found that it was of the same variety as those known to cause the worst kinds of food poisoning. And most disturbing of all was that there was a lot of it.
Had those test subjects kept on using those same bottles, it is very likely that they would have eventually come down with some sort of illness. The only way to prevent this kind of bacteria from growing on and within your bottle is to diligently wash it (if it is a re-usable bottle, that is). If it is a disposable bottle, do as the name suggests and dispose of it after one use. Either way, the lids/tops of water bottles will always carry the most bacteria (because in all cases either your hands or your mouth is in contact with them). If you are truly worried, you can always just pour the water into your mouth without making any direct contact with the bottle (otherwise known as a “waterfall’), which might be worth it despite requiring some extra coordination on your end.