It's hard to determine how much water is too much because we get water from foods and other drinks as well that most people don't include when trying to have the right water intake. The general rule is 6-8 cups a day. However, if you are concerned about drinking too much water, you can add 1/4 tsp. of salt, preferably sea salt, per liter of water. This will prevent an electrolyte imbalance or water intoxication that can occur when people drink too much water.
Probably the best way to tell if you need to drink more or less water is by examining the color of your urine. If your urine is darker than usual- I think everyone pretty much knows what color normal urine is- then you should increase your daily intake. If it is completely clear, you should not increase the water intake and may even cut back a bit.

Drinking the right amount of water isn't really an exact science. They used to push 8 glasses of water a day, regardless, but this was never supported by scientific evidence. Drinking this amount won't hurt you, however, but you don't have to be so regimented about it. The water in your food does count (usually covers about 20% of your liquid needs), as do beverages besides water, even if they have some diuretic qualities (it usually isn't enough to negate the water content--although too much alcohol can make you dehydrated).

Your body also has this handy-dandy little indicator built in to tell you when to drink--thirst. If you are thirsty, you aren't drinking enough water. If you find that you are rarely thirsty, you probably are drinking enough for you. If you are always thirsty, you aren't drinking nearly enough or there is some underlying health issue (like diabetes).

Due to a variety of factors, a hard and fast "8-10" glasses, etc cannot be substantiated. If you are walking in 110 degree heat or are in an endurance race, you will need A LOT of water. Sitting in the cool, not so much. Also certain problems enhance your need for water intake such as Diabetes.

Drink 1/2 your weight in ounces of unclorinated water.

So if you weigh 150 pounds then your daily intake should be 75 ounces.

However as BDteach59 states...there are other factors that should be considered like walking in 110 heat.

Whatever you do not over drink...I did years ago and landed in the emergency room due to dehydration and I couldn't believe it...I drank lots of water each and every day...more than most. I had flushed my body of esstential minerals and just about died.

Zig