Humans should always drink enough water to stay healthy and hydrated and to flush toxins out of the kidneys and body.
Humans need plenty of water but can get by on drinking at least a few glasses of water each day.
As long as you're drinking other drinks it's okay to not drink more than a few glasses of water each day and it's okay to go a day or so without drinking water as long as you're drinking other drinks to stay hydrated.
Some signs that you're not drinking enough water are, persistent bad breath, fatigue, frequent illnesses, poor skin health, dry skin, constipation, sugar cravings and decreased urination.
Nothing bad will happen to you if you don't drink any water for a day as long as you're drinking other drinks such as tea, milk, coffee, soda, orange juice etc.
Actually when you drink something you are indeed drinking some water but the water is in different form of drinks.
You should always drink at least a few glasses of water everyday to stay healthy and keep your kidneys flushed of toxins but it's not gonna harm you at all if you went a day without drinking water.
A human can usually live for up to 3 to 4 days without drinking any water or anything else before they die of dehydration.
As for eating a human can go up to 3 weeks without any food.
But the water is the most important thing a human needs to stay hydrated and live and the food comes second.