There are many recommendations for how much water to drink each day. Most commonly, mainstream media tells us to aim for eight- 8 ounce glasses, or 64 ounces, of water daily. However, this basic recommendation does not take into many factors such as account body size, activity level, gender, age, or medical conditions. There is no "one-size-fits-all" formula for figuring out fluid needs.
Your individual fluid needs vary on a lot of factors that change throughout your life, across seasons, or even daily. Hot weather conditions, strenuous exercise, illness or infection, pregnancy, or living at higher altitudes can increase fluid losses through sweat and respiration; therefore you may need more than the recommended 64 ounces a day. However, if you are fairly sedentary, have smaller body frame or less muscle mass, are over the age of 65, or have a medical condition such as kidney or congestive heart failure (CHF), you may need much less than 64 ounces.
How do you know exactly what you need? For the general healthy individual, make sure to drink enough fluid- all beverages included- so that: 1. You are not thirsty 2. You are urinating every 3-4 hours; and 3. Your urine is light yellow or clear in color. If you feel that you have special fluid needs due to your lifestyle or a chronic medical condition, talk to your doctor or a registered dietitian.
It is possible to become overhydrated as well. This can result in low sodium levels in the blood, a condition called hyponatremia. While this is rare, it is a life-threatening condition sometimes seen in endurance athletes who drink large amounts of water following intense exercise. Even if you aren't an endurance athlete, hyponatremia can occur if you drink large volumes of plain water (over and above your feelings of thirst) and consume a diet very low in sodium. Signs and symptoms of hyponatremia are headache, nausea, vomiting, confusion, muscle weakness or spasms, or loss of consciousness.
General tips for hydration:
1. Buy a reusable water bottle that is 16-20 ounces and carry it with you throughout the day. Aim to drink at least two full bottles a day.
2. Coffee, tea, juice, milk, and other beverages count toward your fluid intake. You also get water from the food you eat like soups, popsicles, and any food that is liquid at room temperature. Some fruits and vegetables are also high in water content, like celery, cucumbers, and watermelon.
3. Water should be your beverage of choice. If plain water isn't appealing, try flavored sugar-free seltzer water, add a squeeze of lemon, or add cut fruit and herbs for a fun twist.
4. If you wake up feeling thirsty, you likely aren't getting enough to drink during the day; However if you are up multiple times per night to use the bathroom, you likely are getting too much.
5. If you sweat a lot during exercise and exercise regularly, you may need electrolyte replacement in addition to water to rehydrate. Discuss your individualized recommendations with your doctor or dietitian.