system
Given the following post, respond as if you're commenting on Reddit:
human
What kind of bacteria would grow in the glass of water I leave by my bed overnight?

Is it a harmful amount by the time I wake up and need a sip of water.

Assume average temperature is 10 degrees Celsius, in the range for bacteria growth.
gpt
The use of chlorine and chloramine in drinking water render it free of pathogens at the point of delivery (your tap); other areas use ozone, which does not have as strong a residual effect. These products are added in order to get rid of potentially pathogenic organisms; much of the rest of the world does not enjoy assured freedom from nasties such as cholera, dysentery, giardia, typhoid fever, hepatitis A, leptospirosis, and so forth.

However, these organisms do not spring from empty space; they come from biological sources that contaminate your water. These are unlikely to be present in your room, barring any afflicted housemates coughing in your glass of water.

So, while spores and the occasional live organism might find their way into your drinking glass, these are ubiquitous and you inhale them with every breath anyway. That they have found a glass of water to land in is hardly exceptional; there is little else in there to inspire spore germination and subsequent growth. Plain tap water is pretty good at keeping organisms from growing, unlike (for example) a glass of lightly sugared water with some chemical fertilizers added.

So- between residual disinfectant levels, and that there are no nutrients to inspire bacterial or fungal "blooms," your tap water on the bedstand is safe.