Doesn't drink by herself?

I've never seen Loki drinking water by herself, only when I hold her and put them next to the bowl. I might not see when it happens, the thing is when I "make" her, she drinks a LOT, which is why I think she doesn't do it.

Is this normal behavior?

She drinks by herself.

Is there any way to know if the snake does not drink by themselves?

If a snake isn't drinking on it's own you would see signs of dehydration, listlessness, lethargy, dry skin (if that makes sense) and obviously problems shedding.
Keep in mind that snakes also soak for hydration when they need too also...and that they are nocturnal so maybe if you sit up at night for a week or so in the dark and have a very dark light so you are still able to see I can assure you that this is when you will see them drink.

Originally Posted by atomic peach

Is there any way to know if the snake does not drink by themselves?

Yes, put a camera on the snake 24/7 and watch the recording.

lol herpanormal activity...the snake possesions : P. Okay enough bad jokes, like everybody else said since your snake is nocturnal she's drinking normally at night it's just not when you see her. It took a long time for me to catch ours in the act but I snuck in one night and found her swimming circles in her water dish and drinking it up. Since then I've caught her dropping her head down from her high hide and drinking from just the surface of her bowl without actually getting in it.