You shouldn’t drink distilled water. It’s devoid of minerals so when you drink it, the distilled water sucks minerals from your body to equalise which can cause issues.
"Since distilled water doesn’t contain its own minerals, it has a tendency to pull them from whatever it touches to maintain a balance. So when you drink distilled water, it may pull small amounts of minerals from your body, including from your teeth."
But that it could be a problem. So its not a myth, that it is demineralizing your body. Its a small effect - but its there, and it could have a negative effect on the body.
I also live in SEA. While distilled water is pretty popular (gaining more popularity these days), spring waters are even more popular and widely available (also tastes better IMO).
https://www.healthline.com/health/can-you-drink-distilled-wa...
The mineral content in even mineral water (never mind tap water) is miniscule.