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Reusing water bottles: Is it dangerous?

Thirsty? If you reach for a handy bottle of water, you’re like millions of Americans who have changed their water drinking habits over the past decade. And I admit I’m one of them. I keep a small water bottle on my desk, and two or three times each day I trek down the hall to the water cooler and fill it up. It seems logical, right? Why spend money on a fresh bottle every day when I have access to an easy fill-up right here at work?

But before you take your next sip of water from a plastic bottle, I have some information that might change the way you quench your thirst. It certainly has changed mine.

Kid hydration

Water is the most natural and necessary beverage you can put into your body. But as we’ve seen in other e-Alerts (such as last summer’s “Where The Yellow Went” 7/15/02, about the dangers of fluoridation), the contents of the water you drink can have a significant effect on your health. So it’s no wonder that people have turned away from straight tap water which often contains high levels of lead, chlorine and who-knows-what-else?

Now, two recent studies from Idaho and Canada bring important warnings for the millions of people who enjoy their water in convenient plastic bottles. First the good news: I’m not going to tell you bottled water is bad for you. But you may be surprised to find out that what you do with the bottle after you’ve drained it might lead to serious health problems.

Researchers from the University of Calgary collected water samples from 76 plastic bottles used by students in a Calgary elementary school. About one third of the samples contained bacterial contamination severe enough that, had the water come from a tap, health officials would have issued a “boil water” advisory. Some samples even contained fecal coliforms. Cathy Ryan, the lead professor of the study, noted that if fecal coliforms were found in a town water supply, it would have to be shut down.

These contamination problems are a direct result of reusing water bottles without proper washing between each use. The researchers speculated that the contamination of the elementary school water bottles was likely complicated by insufficient hygiene – specifically, a lack of thorough hand washing. Nevertheless, any water bottle reused again and again without washing is subject to contamination with bacteria.

Cleanliness doesn’t guarantee safety 

A University of Idaho survey revealed that the reuse of water and soda bottles was widespread on the UI campus, with some individuals using a single bottle for several weeks. One participant reported that they had reused the same bottle for six months. This survey was taken in conjunction with a graduate program study that examined the effects of repeated bottle use.

The UI study tested water samples from typical soft-drink and water bottles made from a plastic called polyethylene terephthalate (PET). Analysis of the samples showed that with repeated use, toxic chemicals in the plastic can break down and migrate into the liquid inside. One of the toxins that appeared with regularity was di(2-ethylhexyl) adipate, a carcinogen that has been shown to cause liver damage and reproductive problems.

Furthermore, when bottles were used repeatedly, the concentration of toxins gradually became more pronounced. And ironically, washing the bottles didn’t help – in fact it only made matters worse. The UI data suggested that the break-down of toxins was accelerated by regular exposure to hot water and soap.


So the water bottle dilemma has some similarity to the problem with tap water. Lead in water pipes is drawn into the water just as the toxins in plastic are drawn into the bottled water. The difference, of course, is that you have far more control with bottled water. And in most cases, bottled water is less contaminated than tap water.

As these studies demonstrate, it’s probably not a good idea to stick with one bottle for very long – even if you clean it after each use. I’m really not trying to boost sales for bottled water, but a fresh bottle every couple of days would seem to be the wise way to quench.

Of course, you can always take your water the old-fashioned wayin a glass.

To Your Good Health,

Jenny Thompson
Health Sciences Institute

“People who frequently reuse water bottles may be risking their health” Jen Horsey, Canadian Press, 1/26/03