PORTLAND, Ore. -- Doctors and trainers all agree drinking water is crucial, but the push to improve the environment is changing the way some people stay hydrated.

Many people have turned to reusing water bottles, rather than using a new one every day. Bette Darnall said she stays away from mass-produced plastic water bottles entirely.

“I’m really trying to live as green as I possibly can,” Darnall said.

Darnall, like many others, uses the same bottle every day.

Meanwhile, Dave Dunford said he has used his water bottle for a month and hasn’t washed it once.

So what’s lurking in their H20?

Tests at Coffey Laboratories in northeast Portland showed Dunford’s bottle had 99 bacteria colonies in the water.

Darnell’s bottle was swimming with 2,000 bacteria colonies, which biologists said is still acceptable.

Two other bottles that were tested came in worse, however.

A bottle washed the day before the test contained 2,400 colonies.

But it was Amy Blue’s bottle that topped the list.

While she washed it a few days before the test, the bottle contained 4,100 bacteria colonies.

Blue only uses her water bottles for a couple of days at a time, but said the high number could be linked to her young son, who sometimes gets his hands on the bottle.

She said the results were a good reminder about staying healthy.

“It might make you think twice about not wanting to keep that in your system on a regular basis,” Blue said.

A toxicologist at Oregon Health & Science University recommends people wash their bottles with warm water and a mild detergent.

Over time, the bottles develop cracks and crevices where the bacteria can easily collect. He said it’s important people swap out their bottles as much as possible.