Lifestyle Wellness
Water Bottles Lew Robertson/iStock

Disposable plastic water bottles.

June 01, 2016

Infrequently Asked Questions: Will reusing a plastic water bottle actually make you sick?

The world is full of questions we all want answers to but are either too embarrassed, time-crunched or intimidated to actually ask. In the spirit of that shared experience, we've embarked on a journey to answer all of the questions that burn in the minds of Philadelphians — everything from universal curiosities (Why do disposable coffee cups still leak?) to Philly-specific musings (How does one clean the Liberty Bell?). 


Sure, it's convenient to just refill that disposable, plastic water bottle. But is it healthy?

In search of the definitive answer, we reached out to Dr. Neilanjan Nandi, associate director of the Gastroenterology Fellowship program at Drexel University College of Medicine.

Is it OK to reuse a disposable water bottle?

The short answer is really no, it’s not a good idea to reuse disposable water bottles. This is actually quite a common question I get among my demographic of patients in my GI clinic, because I see a lot of use, actually.

A lot of people think ‘Oh, I’m recycling, saving the environment, etc.' But what they’re also doing, potentially, is they might be harming themselves. Most of the plastic used to make disposable water bottles is not made to be used again, in terms of regular wear and tear. So the regular act of washing, if they're washing it, can damage the plastic. And some put them in their dishwashers, and that high heat actually causes chemicals to leach from the plastic into the water — that can be dangerous and hazardous to their health. If you hold a plastic bottle up to the light, you won’t see any physical damage, but there are micro-cracks that develop. And micro-cracks actually harbor lots of harmful types of bacteria. If you look at your hand, you and I have about 10 trillion human cells — our body has about 100 trillion bacteria in it. These bacteria are almost completely imperceptible to the eye. And they can line these tiny cracks and grow there and form biofilms. And the types of bacteria that form are from our mouth. And our mouth, ironically, is full of very dangerous bacteria. That bacteria is normally killed by our stomach acid, but if we’re exposed to too many amounts, it can have harmful effects. So the cracks, just from regular wear and tear — washing, dishwashing — these things can actually harm the plastic and allow bad bacteria to grow. And so you're constantly refeeding your body these bad bacteria, and that’s not a good thing long term.

So it’s not just the chemicals in the plastic, it’s partly the bacteria coming from our own bodies?

Exactly. And if you had to rank which is more important — we talk about BPA being leached into certain types of plastics. If you ever turn over a plastic bottle and look, or a plastic bag — anything made of plastic has a triangle and an arrow and a number in the middle, and that corresponds to different types of plastics approved to make that type of product. A bag, a cup, a vessel or Tupperware. Several of those types of plastics can leach BPA, which can be harmful to the body and shown to be carcinogenic, so we don't know truly — there is some small longitudinal data on this, but not 20 or 30 years of data. Maybe 10 to 15 years of data that shows the cancer is there. But you can leach the chemical into the water by exposure to sunlight. And how often does that happen? Often. Exposure to high heat — if you buy that pack of 30 bottles of water and you put it in your car in high heat before you get home, you could be [releasing chemicals]. And then the dishwasher, that’s the highest heat possible — that accelerates a lot of chemicals leaching into the water. People who drink from those bottles of water, they can show there are elevated amounts of BPA in their urine after just a week of drinking that water. Can you believe that? And that’s short term ...

But the highest risk is not these chemicals being leached; it's actually just regular use — wear and tear — that is the highest risk. And the risk is infection.

What about sink and soap?

One would think that is safe, but actually, the detergent we use oftentimes can be harmful to the plastic. And when you use any type of sponge, porous or not, it causes scratches to form in the plastic — plastic is soft. It’s a soft material. You may not see it, but there are biofilms that form. And the common places it forms are right at the mouth of the water bottle. Most disposable water bottles are actually very difficult to clean because you can’t get inside the water bottle without a sponge. And even if you do, you can scratch it.

Reusing this is actually not a safe idea long term.

What if you’re doing it once?

Once within the same day, as long as you’re being reasonable, is fine. But it should not be used more than a day. It really shouldn’t. 

Dr. Nandi: The simplest thing to do is use reusable things like stainless steel and glass. They’re very easy to clean and good for the environment. 

A couple years ago they did a study with elementary school kids and took their water bottles — elementary school kids using water bottles again, their parents were letting them, and they cultured the water bottles and found there were excessive amounts of bacteria from your gut colonizing these water bottles. You might think, ‘Where are they coming from if the parents are washing them and giving them to kids again?’ One, the washing is not safe. Two, is kids, unfortunately, don’t wash their hands when they go to the bathroom. A lot of these were fecal coliform bacteria. That’s a scary thing, too — kids aren’t doing it and a lot of adults don’t wash their hands properly after they go to the bathroom, and they can pick [bacteria] up on surfaces, etc., so there are a lot of reasons why it’s unsafe to reuse these water bottles repeatedly.

What illnesses is this associated with?

Most of the times it’s going to be gastroenteritis. It’s a broad word to describe any type of syndrome that causes inflammation or infection of the intestine — usually the stomach or small intestine. Nausea, vomiting and diarrhea [are the common symptoms]. That’s the most common type of thing you might have. How often are those presented clinically to the doctor’s office or clinically to the hospital, even? Very rare, because many of these are self-limited. It’s like food poisoning: You go out, have bad food at a restaurant and it gets better in a few days. So there’s limited time to get to a doctor’s office. But nobody wants to be sick more than they have to be.

Anything to add?

The question I get most is ‘Doc, I thought I was helping the environment, what do I do?’ Well, ironically, by washing you're wasting more water and introducing more detergent into the water supply. I’m sort of an eco-warrior, so I like to preserve the environment as much as I can.

The other thing I get is, ‘If I can’t reuse the plastic water bottle, what do I do?’ The simplest thing to do is use reusable things like stainless steel and glass. They’re very easy to clean and good for the environment. 

Another thing is to always air-dry. If you are the type who wants to use disposable plastics, air dry. If you don’t, that moisture helps breed some of these biofilms, or harmful bacteria.

The other thing about bottled water that’s interesting, is bottled water doesn’t contain fluoride. The introduction of fluoride into the American water system actually dropped the rate of tooth decay — cavities — dramatically. By drinking regular city water, which is more regulated than bottled water — bottled water is not very regulated. I don’t know if you know that. It’s more regulated and more pure, ironically. The miseducation the public is given by certain powers that be, and they want you to think bottled water might be healthier. But it’s not very regulated and lacks fluoride. That's important because there could be an increased rate of tooth decay. And where are the reports that document the health of the water you’re drinking from that water? Not that bottled water is necessarily dangerous, but it’s food for thought.


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