Figure out if your sense of thirst works (part of interoception). If you can go hours without getting thirsty, it might not be working so well.

If your “thirsty don’t work” then building in a hydration habit is important to avoid dehydration.

Ted Ed: What would happen if you didn’t drink water? – Mia Nacamulli – YouTube

Habits: https://youtu.be/PZ7lDrwYdZc 
Effective practice: https://youtu.be/f2O6mQkFiiw

Water | Bunny’s Info-Dump (sweetpeastudio.biz)

Water Calculator: Water Intake Calculator – How much water should you drink per day? (gigacalculator.com)