Hair Problems = water’s fault?

Ever since I moved to Japan I’ve been getting more and more dandruff on my scalp. I don’t know if it’s the water or the shampoo and it’s getting frustrating tbh. Is this the water’s fault? Or is it just the shampoos I used? Any recs for shampoos? Usually I can go for 2-3 days without washing my hair but now I feel like I should wash my hair everyday 😭😭😭

Edit: thank you all for your suggestions. I forgot to mention a few details here.
1. I am a SEAsian
2. I have wavy (originally curly) and thick hair
3. Been using a lot of warm/hot water for showers. Especially during winter.

Again, thank you for yiu advices! I’ll try to follow the suggestions everyone’s given me.

by KeyMewTaroEX