Are plastic water bottles that we reuse over and over again also filled up with bacteria?


Yes, a laboratory test of multiple plastic water bottles revealed bacteria levels higher than what the EPA would deem acceptable. But, in most cases the bacteria that builds up by reusing water bottles won’t hurt you at all.

More News

Next Story

Not Available

Just For You

Not Available


Not Available

Aerobiology Laboratory in Dulles, Virginia
Microbiologist Amy Sapkota with the University of Maryland School of Public Health


It all started as a simple e-mail from Bernie Gilliam, but then transformed into a months-long journey to find out the answer to her question.

Is it safe to drink a bottle of water and then fill it up to use again?

We kicked things off with a Verify house call to the Alexandria, Va., home of Bernie and Toronto Gilliam. The couple doesn't see eye-to-eye on this matter, with Bernie’s husband claiming he saw somewhere that it’s unsafe to use a water bottle and then refill it.

Bernie says she typically fills up a fresh batch of bottles each week and only re-uses them a couple times before tossing them in the recycling.

“I just refuse to throw them away the first time. It just doesn’t make sense to me. Water is already in them. Why not fill them with water again?” she explained.
So the Verify team took Bernie’s water bottle, along with an assortment of other bottles, to Aerobiology Laboratory in Dulles, Va.

Lab supervisor Manju Pradeep described the testing process for Verify.

“We fill the bottles with water, we culture it for 72 hours to make sure if there is any bacteria growing in it,” she said.

There are microscopic “bits” of bacteria in our water and the EPA says anything less than 500 “bits” in your tap or bottled water is acceptable. Because it’s microscopic, you can’t see them but the lab test reveals the truth.

A few weeks later, Verify collected the bottles from the lab and revealed the results to Bernie and her husband.

Spoiler alert: The results were nasty.

Before the test, WUSA9 anchor Adam Longo had been reusing the same water bottle, which he nicknamed ‘McNasty,’ for about six months.

The test revealed 2,560 microdots of bacteria in Longo’s water bottle, well above acceptable levels.

But Bernie’s water bottle was the nastiest of all.

“I was right,” Toronto Gilliam exclaimed during the big reveal.

The lab test found 4,680 microdots of bacteria, nine times the EPA’s acceptable amount.

“I’ll recycle the water bottles, no more reusing water bottles,” Bernie told her husband.

So it’s Verified that our reused plastic water bottles are loaded with bacteria….but there’s a catch.

If the water bottles are filled with bacteria, why aren’t we getting sick?

We turned to Microbiologist Dr. Amy Sapkota from the University of Maryland School of Public Health for the answer. She explained that the bacteria introduced into the water bottles is coming from our own mouths.

“It’s very likely we have more bacteria in our mouths than there are people on Earth,” described Dr. Sapkota. “So we ourselves are loaded with bacteria, but in most cases these are non-disease causing bacteria, non-pathegenic bacteria.”

So even the nastiest water bottles from our test wouldn’t make the person sick.

“It’s highly unlikely you have a disease causing organism in that water bottle,” she said.

Dr. Sapkota says your chances of getting sick do increase if you share a water bottle with someone else.

So while we can Verify that reused bottles are riddled with bacteria, we can also Verify your chances of getting sick are extremely low if you’re the only one drinking from that bottle.

In this case, Bernie and Toronto were both right.