Drinking the infamous 8 cups or 2 liters of plain water a day is enough for most people involved in short bouts of low-intensity exercise. Once normal conditions change the needs for hydration change as well. We add extra cups of water when

• the air is drier
• it's hotter
• we've had alcohol
• we've been sick and losing water through diarrhea and/or vomiting
• we've been sweating 
• we're involved in long duration and/or high-intensity training

 Fitness fanatics and athletes consume extra water thinking that more of a good thing is better and carry around a refillable gallon bottle. These folks, in particular, are at risk of experiencing a condition when their bodies' sodium is diluted by the excess H2O. 

This is known as hyponatremia and is a quite common side effect of going overboard with hydration. Its mild symptoms include nausea, headache, dry mouth and lips, and restlessness. Yes, all the symptoms of dehydration. Can we say, then, that drinking too much water dehydrates you?

Here is how to avoid it:

#1. Don't chug a lot of water at once. 

#2. When replacing a lot of fluid, or drinking more than 2L of fluids a day, start adding an electrolyte drink (Pedialyte or a sports drink).

My favorite is one scoop of electrolyte powder into my water bottle.  Look for one with D-ribose to improve the delivery of electrolyte-rich blood to the heart and working muscles. 

#3. Determine your water needs:

Beginners and everyday exercisers will hydrate well consuming 1-2 glasses of water at each meal. They will benefit from an extra glass when feeling thirsty or during exercise.

Numbers Guys can calculate their needs based on the bodyweight. Ingest 30-40 mL of water per each kilo of bodyweight. Add 1L of water with added electrolytes during a hard-core training session.