Ok, so it's bad for the environment to buy single-use plastic water bottles like Aquafina. But what if you reuse them again and again?

A reader recently asked whether that's a bad practice after I wrote about metal water bottles. I know I've done it in the past.

Renee Hackenmiller-Paradis at

said there are two big reasons people shouldn't reuse single-use plastic water bottles. The main one is that bacteria can easily contaminate the bottles since they're hard to thoroughly clean with all the ridges and indentations, and they can't be put in the dishwasher. The other big issue is that they're made from polyethylene terephthalate, and over time that can degrade and leach phthalates into the water.

Like Bisphenol A, phthalates are endocrine disruptors, and Hackenmiller-Paradis said studies have linked them to various health problems, including women giving birth to boys with small genitalia and undescended testes.

Refilling a single-use plastic water bottle once is probably fine, but that "repeated use and it sitting around with the backwash in it -- that's the health hazard," said Hackenmiller-Paradis.

And if that isn't enough bad news about single-use plastic water bottles, she also told me this: a one-liter plastic water bottle uses 6.74 gallons of water in production and transportation. The production and distribution of that single one-liter bottle is responsible for 1.2 pounds of greenhouse gas emissions.

Hello, Klean Kanteen.

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