Both water and sunlight are important components required for the proper functioning of the body. It is often said that drinking water exposed to sunlight can increase your energy and rejuvenate your body.
On the other hand, drinking water from water bottles exposed to the sun has a negative effect on the body. It is due to the presence of the industrial chemical BPA or bisphenol-A in plastics, which is harmful to the body. While most plastic water bottles don’t contain this chemical, BPA is found in polycarbonate bottles. Another adverse effect on drinking water exposed to the sun is that it can increase the growth of harmful bacteria, depending on the species, due to the extreme heat from the sun.
A study published in the journal Food Chemistry investigated the effects of sunlight exposure on chemical migration in PET-bottled waters. The researchers used PET-bottled normal water and carbonated water. The bottled waters were exposed to sunlight and examined on days 2, 6 and 10. The result was that PET-bottled normal water posed no harmful effects when exposed to sunlight, as no aldehydes were detected. But, the carbonated water had developed certain harmful effects on exposure to sunlight. Because the carbon dioxide in the water fuelled the chemical migration
However, another study conducted by researchers at Arizona State University in 2008 showed how extreme levels of heat increased the release of antimony (a regulated contaminant) in PET bottles. The National Institute of Health (NIH) states that extreme doses of antimony can be toxic. The researchers examined the antimony leaching at different temperatures. During summers, the temperature inside of cars, enclosed storage areas, and garages can rise to 65 degrees Celsius (in Arizona), which can promote antimony leaching from PET bottles. But, only a small amount of the antimony in PET bottles was released into the water. In 2014, scientists found high levels of antimony and BPA in PET water bottles in China. And in 2016, researchers found high traces of antimony in water bottles in Mexico. For both the studies, the water was tested in conditions that exceeded 65 degrees Celsius, resulting in worse problems.
According to the International Bottled Water Association, bottled water should be kept in the same conditions as groceries. To be on the safer side, drinking water from plastic bottles can cause a host of health problems. So, the alternative way is to drink water from copper, steel or glass bottles as they possess certain health benefits.