Is it safe to reuse plastic water bottles?

First I think it important to answer whether or not it is safe to drink from a single-use plastic bottle. The water in a plastic water bottle being used for the first time is already contaminated with plastic and chemicals making your city or well water safer to drink. However, the safety and cleanliness of your city or well water depends on where you live. If you live somewhere that does not take the safety precautions required to provide safe city or well drinking water, then yes, bottled water is your best option. However, much of the water provided through city water or well systems for those living in developed nations is safe to drink and often times safer than drinking from single-use plastic bottles. City water is also more heavily regulated that bottled water. Bottled water is not regulated, at least in the United States, unless the water is bottled in one state and then transported over state lines. If this occurs, then there is one regulation required by the FDA. City water must pass through tens to hundreds of regulations and safety tests before it reaches your tap.

The water inside a single-use plastic water bottled is contaminated in several ways. First, the process required to make and fill water bottles can cause microplastics contamination. A recent study found that all bottled water contained microplastics. Microplastics enter the water in the water bottle in two ways. First, it is known that the water put into bottle water already contains microplastics since microplastics are present in all of our freshwater sources, even the ones used for drinking water. Second, the creation of the bottles and caps leaves microplastics in the air or on the equipment used to make water bottles allowing for a second round of plastic contamination. A study conducted by researchers at the University of New York in Fredonia, and presented by the World Health Organization, found twice as many microplastics in bottled water as they did tap water. But does having plastic in your water make it harmful? The answers for its effect on humans is still unclear, but research conducted on fish and zooplankton (microscopic marine and aquatic animals) has shown plastic ingestion and contamination has effects on the hormones and life cycle patterns of these organisms. The growth, feeding, and reproduction patterns for these organisms is different when they are known to be contaminated with plastic. We still do not have research to prove similar effects on humans, but we do know the chemicals used to make plastic and proven to be leached from plastic, through heat or sunlight exposure, to be endocrine disruptors and carcinogenic.

Next we move to the second method in which bottled water becomes contaminated. Bottled water is already contaminated when it leaves the factory, but then all bottled water is shipped to places for consumer purchase. In transport these bottles are able to heat up since they are not shipped in containers that are kept cold. When plastic heats it releases all the chemicals that are used to make it. As I mentioned earlier we know the chemicals used to make plastic are endocrine disrupting affecting our hormones and other body functions and cancer causing. Therefore, these chemicals leach out of the plastic and into the water you will drink. The more exposure the bottle has to heat the more chemicals released.

Lastly, many people think it is ok to reuse a single-use plastic bottle more than once. Research has shown that this behavior is unsafe. The plastic used to make bottles is very thin and consequently subject to cracking due to a weaker structure. These cracks can harbor bacteria and lead to unsafe drinking water. Washing the bottle in hot water, like your dishwasher, can lead to more cracks and cause the plastic to leach chemicals (Cooper et al., 2011).

In conclusion, as a consumer you must first consider whether it is safer for you to drink bottled water or water from your tap based on where you live. I suggest doing research to better understand the safety regulations required by your local water treatment facility to determine the cleanliness of your water. Then if you choose to use a bottle to refill your water I suggest you use one made of a thick plastic that is not subject to cracking or a metal or glass bottle.

References

Cooper, J.E., Kendig, E.L., and Belcher, S.M. 2011. “Assessment of Bisphenol A Released from Reusable Plastic, Aluminum and Stainless Steel Water Bottles”. Chemosphere. 85 (6): 943-947. 

Mason, S., Welch, V., and Neratko, J. 2017. “SYNTHETIC POLYMER CONTAMINATION IN BOTTLED WATER”.