At some point, you've probably looked at that empty water bottle in the backseat of the car and wondered if it's got just a little more life in it.

After all, if you're going to use plastic, why not make it at least double-use plastic — rather than add to the mountain of one-hit wonders.

The most well-intentioned among us might even try to turn it into triple- or quadruple-use plastic.

But there's a price on those good intentions, especially when it comes to your health.

The thing is, most single-use water bottles are made from polycarbonate plastics, a pliable and transparent material that would seem ideal for water vessels. And most of those bottles are produced using a chemical compound called polyethylene terephthalate, or PET.

Bottles made with PET have long been considered a safe alternative to the much more studied — and vilified — alternative, Bisphenol-A, or simply BPA.

In fact, manufacturers proudly tout their bottles to be BPA-free. And that's for good reason. Several studies have linked BPA to health woes ranging from cancer to heart disease to even behavioral issues. BPA was found to mimic hormones that can create havoc in the human body.

But more recent research suggests BPA-free alternatives may not be such saints after all — and in fact may pose similar health threats.

The trouble is chemical compounds don't stay baked into plastic. They're known to leach into the water itself. A study from the Harvard School of Public Health found that people who drank for a week from polycarbonate bottles had a two-thirds increase of BPA their urine.

And those were the results from one-time usage of plastic bottles. What happens when you flush them repeatedly with refills of water? It's easy to imagine more of those chemicals leaching into the water over time.

Then there's the problem of microplastics.

Last year, scientists from the State University of New York tested 259 containers of bottled water and found tiny pieces of plastic in 93 percent of them. Scientific opinion on whether ingesting plastic, however, remains divided. Some experts suggest the human body is perfectly capable of flushing out contaminants like microplastics.

Even the World Health Organization categorizes the risk from drinking microplastics as "low" — although it hastens to add that more research is needed.

The older the bottle, the bigger the problem

Water bottles in recycling bin. It's tempting make plastic water bottles more than a single-use item. (Photo: Alina Avula/Shutterstock)

One thing that we know for certain is that, regardless of the type of plastic, a water bottle collects a lot of dings, dents and creases as it's reused. And those nicks could increase the chances of chemicals leaching into the water.

Experts warn that "everyday wear and tear from repeated washings and reuse can lead to physical breakdown of the plastic, such as visible thinning or cracks."

Then there's the problem of bacteria — something that also happens to thrive in cracks or dents, thanks to the difficulty of washing those nooks.

While all bacteria isn't necessarily bad, it's probably safe to say you don't want to ingest it on the regular.

The bottom line? If you really want to be a hero to both the environment and your body, reusing a plastic water bottle probably isn't a good idea. Instead, get out that stainless reusable water bottle that's been in the cabinet and fill it up.

The best thing you can do is skip bottled water entirely, especially as research continues to pile up on the potential hazards of drinking water from any kind of plastic.

As Shanna Swan of the University of Rochester School of Medicine and Dentistry, told the Australian Broadcasting Corporation. "This is coming at a good time because the use of bottles for consuming water is getting very bad press now because of its carbon footprint.

"It's just another nail in the coffin of bottled water, the way I see it."

Should you be refilling that plastic water bottle?
It may sound like a good idea for the environment, but refilling a plastic water bottle may not be a good idea.