You know what? I honestly don't know, however, some sugar substitutes are far unhealthier than actual sugar.
If you're going to use a sugar substitute, opt for a natural source like stevia, agave, or black strap molasses (btw, black strap molasses has many wonderful health benefits - see for yourself: http://funadvice.com/r/1687sibcrgg.
At any rate, regardless of whether or not you're going to be consuming sweets, you should be drinking your minimum of 8 glasses of water a day to make sure you're not getting dehydrated.
Little known fact: When the body is dehydrated, it goes into survival mode and stops sending signals that you are thirsty. If you're not thirsty, it means you need to drink.