Washing your hair everyday especially twice per day can wash out the natural oils that your hair needs.
If you need to clean your hair more than once per day you should just rinse your hair out with plain water and avoid using shampoo.
I only wash my hair with shampoo 4 times per week which is more than enough since my hair doesn't get that dirty.
The oils that your hair has naturally is needed for healthy hair so avoid washing your hair everyday to keep your hair healthy.