When someone stops drinking water, over time they get dehydrated even though you may not FEEL dehydrated, then it starts to affect their body where they start to retain water and all kinds of other things get out of whack. Most people who are dehydrated don't even know it. Some have gone so long without drinking the right amount of water that they don't even realize that feeling is dehydration, they think it's their normal every day feeling. That's why when someone goes to the doctor or emergency room the first thing they do is give them IV and liquids because most people are dehydrated and don't know it. Dri nking pop and other liquids is not the same as getting plain water. Not enough water also affects the kidney function too. Water keeps your system flushed out and purified. So if someone stops drinking water, they may not feel a difference but it does make a difference. And if you live where it's hot, you better really make sure to drink plenty of water!