Fungus in my Nalgene?

I washed and left a Nalgene bottle opened, by a window, to dry.

A couple of days later I noticed fungus growing on the inside.

Now I have a very basic understanding of fungi, but I always thought they decomposed organic matter. So, what was it doing in my Nalgene bottle? I imagine some water may have condensed on the inside, but can a fungus live on water alone?

whatever it’s growing on doesn’t have to be visible to the naked eye. You might have missed a spot or the water may have enough nutrition in it for the colony. Wash the bottle with scalding water and lots of soap. And be sure to get in their and scrub.

Respect the power of the fungus. They can live happily on virtually nothing, to the extent that fungus growth inside camera lenses is a widely recognised problem. Compared to the inside of a camera, a nalgene bottle is a buffet table.

Is that anything like schpilkus in your genechtagzoint?

Get some hydrogen peroxide and go to town. The peroxide will A) kill the bacteria and fungi and B) decompose any organic material clinging to the plastic surface. The nice thing about peroxide is that it will then C) decompose to water, oxygen, and hydrogen leaving no off flavors.

Bleach will do A and B only.

My guess is that you have a thin layer of organic residue in the bottle, especially if it is a narrow-neck. Remember, Nalgene is autoclavable. If all else fails, you can pressure sterilise it. (Really, I wrote the company and asked. You can autoclave them if they are the clear ones and you leave the lid open)