I think you came from kerala. In kerala all water is herbal mixed. But here it is full of chemical treated water.Sea water treated for common use. So all chemicals are available in the water.Dont take hot water directly to your head. As the above people told stored cold water can be used for head bathing. Avoid stress.But it can not be avoided here.So do yoga for peace of mind.
Dont go out in hot sun.
Use herbal shampoos. But this experience will teach you how to avoid hair fall in future.