Dear Dr. Roach: Please write about the correct amount of water that people should drink. There’s so much misinformation! — E.N., MD

Answer: There is so much misinformation since a simple answer, like “more is always better,” is easier than a nuanced answer. It depends on your age, activity level, the temperature and humidity, any medications you might be taking, and whether your kidneys have any issues. However, the simplest answer, which is true for most people, is that your body has a built-in system, called the thirst reflex, to make sure that you are getting enough fluid. There are only a few times when you should override this system.

The most important exception is in older people, who sometimes have a decreased thirst mechanism. This is particularly the case in people who live in long-term care facilities or those who have physical or cognitive disabilities. As such, reminders to drink a reasonable amount (1.6 liters or about seven 8-ounce glasses for women; 2 liters or eight 8-ounce glasses for men) of all liquids during the day can be helpful. (Alcohol, of course, isn’t helpful and can be harmful to a person’s fluid status.)

People who are taking diuretics do not need more water. In fact, excess water drinking while on most diuretics can lead to abnormally low sodium levels. Another way to tell if you are getting enough water is the volume and concentration of your urine. People should generally void every few hours, and the color of the urine shouldn’t be dark. Needing to urinate less frequently or having concentrated urine should be an indication for a person to drink a few glasses of water.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu.