Chronic dehydration can lead to a multitude of health woes. Turn on the proverbial faucet and make sure you get enough fluids every day; they come not only from water but from food sources.

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Water is one of the health essentials you probably don’t think about much, but chronic dehydration can have significant impact on your well-being. Furthermore, we wouldn’t survive long without it. Water makes up about three-quarters of our body weight; we obtain it via the fluids we drink (obviously!), and from foods, particularly fruits and vegetables.

In theory, chronic dehydration should be avoidable due to the sensation of thirst, which kicks in if your brain senses that you are deficient in water. This corrective trigger relies on sensitive body-wide detectors that are linked by neural pathways to the brain, and it doesn’t just need chronic dehydration to kick it into gear. It should activate if you’re even just a few hundred milliliters short of water.

But most of us don’t wait to drink until we’re excessively thirsty from chronic dehydration—instead, we consume fluids in more general ways:

• “Washing down” meals and snacks with beverages like coffee, tea, and milk
• Warming ourselves in the winter with bowls of soup
• Cooling down in the summer or after exercise sessions with a cool drink
• Seeking out the pleasurable buzz we get from caffeinated soda or an alcoholic drink (though beware: Large amounts of alcohol can cause you to become dehydrated).

Who’s at Risk for Chronic Dehydration?

Some of us are at particular risk for chronic dehydration. This category includes older adults—their ability to regulate thirst and fluid intake wanes as they age, and their fluid intake and hydration levels can be further complicated by disease, dementia, poor mobility, and medication side effects (diuretics, which are used to treat heart failure and high blood pressure, are a major culprit).

In order to protect themselves from chronic dehydration, seniors should be proactive about drinking water even when they don’t feel thirsty. (See our post “Confused About How Much Water to Drink? A Myth-vs.-Reality Check.”)

How Chronic Dehydration Affects the Body

Chronic dehydration affects the body in a number of ways.

• Chronic dehydration impacts physical performance. If you’re playing a high-intensity endurance sport, particularly in hot weather, you lose large amounts of body fluids via sweat. If you don’t replenish what you lose, your physical performance can decline. You may notice that your endurance is less, and feel as if you have to work harder than usual. Your motivation may be sapped, and you may experience fatigue. Dehydration can persist for several hours after engaging in rigorous physical activity, and it may be worse if you’ve suddenly started engaging in sports again after a period of being sedentary, or you aren’t acclimatized to hot weather. Children are also vulnerable to dehydration during physical activity, since they may not recognize that they need to drink.
• Chronic dehydration affects your brain. Chronic dehydration—even if it’s mild—can impact your mood and your cognition. Your ability to concentrate, your level of alertness, and your short-term memory may be noticeably affected.
• Chronic dehydration raises the risk for delirium. Delirium is an acute brain attack due to a problem in the body that alters mental status. It’s common in the old—red flags include inattention, rambling, incoherent, and/or illogical speech, and an altered level of consciousness (a person with delirium may be hyper-alert or drowsy).Other symptoms include new memory problems and emotional disturbances, which may appear as fear, anger, anxiety, depression, paranoia, irritability, or euphoria. Physically, a person with delirium may be hyperactive and very agitated—some even experience hallucinations. Several underlying factors can cause delirium (for example, having some degree of cognitive impairment, being frail, having a sensory impairment, such as poor vision or hearing, and being malnourished. Another common cause is chronic dehydration.
• Chronic dehydration causes gastrointestinal problems. Chronic dehydration is a major factor in constipation, since stool absorbs water in the gastrointestinal tract and without sufficient water digestion slows down and stool becomes hard. Studies suggest that in the old especially, low fluid intake predicts acute constipation, and seniors who drink the least have more than double the risk for constipation. Gastrointestinal upsets also can result in chronic dehydration due to diarrhea, with children especially at risk.
• Chronic dehydration harms your kidneys. Your kidneys require sufficient water in order to properly filter waste from your blood stream and excrete it via urine. There is a lot of evidence showing that good hydration levels are associated with less risk of urinary tract infections.
• Chronic dehydration can affect your heart. Your blood volume can be decreased by chronic dehydration, and the resulting shortfall means your heart has to work harder. Your blood also will retain more sodium of you have chronic dehydration. Research suggests that good hydration is linked to a lower risk of heart disease and blood clots.
• Chronic dehydration causes headaches. Many people suffer from dehydration headaches, and chronic dehydration also may trigger migraines. While drinking water can help ease the intensity of a headache caused by chronic dehydration, it isn’t clear whether regularly drinking more actually helps prevent them.
• Chronic dehydration dries your skin. Your skin is about 30 percent water, and its water content is what makes it retain its elasticity and look plump and healthy. A giveaway sign of chronic dehydration is skin that stays tented if you pinch it. Drinking enough helps your skin stay hydrated, but it won’t help you avoid wrinkles.

How Much Water Should You Drink to Avoid Chronic Dehydration?

Women should aim to consume about 91 ounces of fluids per day, and men should get about 125 ounces, according to the Institute of Medicine. See also “Dietary Reference Intakes: Water, Potassium, Sodium, Chloride, and Sulfate” at the National Academy of Sciences’ website.

You can factor in all the fluids you consume, not just water (so you can count beverages and fruit juices, for example), and you can also count fluids you get from food (such as soup is an obvious example, and fruits and vegetables that are high in water, such as watermelon, apples, grapefruits, lettuce, and broccoli).

Aim to take in more fluids in hot weather, when you are exercising, and if you have any kind of gastrointestinal upset that causes vomiting and/or diarrhea. If you are dehydrated due to the latter, you also might want to replenish your electrolyte levels. Electrolytes include sodium, potassium and magnesium, and a proper balance is crucial for many bodily processes, including heart function.

This article was originally published in 2017. It has since been updated.