Amid our fast-paced lifestyles and doomscrolling addictions, hydration needs are the first to be ignored. For this basic survival need, there are now reminder apps, fancy bottles, checklists and whatnot. Many young people even take pride in not being able to drink enough water, putting “hustle, dreams, ambitions” first.As per the 2025 Dehydration Statistics report, approximately 16-21% of people worldwide exhibit dehydration symptoms such as thirst, dry mouth, and decreased urination. The issue isn’t as trivial as it seems. This small habit of not drinking water can affect the body in more ways than commonly perceived. To fully understand the extent of dehydration-induced health problems, we reached out to a few medical experts. Here’s what they have to say.What happens to the body if someone drinks only 500 ml of water a day?Ipsita Chakraborty, Senior Nutritionist at Hungry Koala, explains that consistently consuming just 500 ml of water per day can lead to mild to moderate dehydration. “The body responds by reducing urine output and drawing water from cells, leading to symptoms like dry mouth, fatigue, dizziness, and constipation.”Story continues below this adOver time, chronic dehydration can impair kidney function, increasing the risk of urinary tract infections, kidney stones, and even renal decline. “Blood volume may also drop, affecting cardiovascular function and thermoregulation,” she adds.While water from foods and other beverages can partially contribute to hydration, Ipsita stresses that it isn’t enough to make up for such a low intake. “Water-rich foods like fruits and vegetables, or drinks like milk and juice, provide some hydration, but pure water is still the most efficient hydrator,” she clarifies.How does chronic low water intake affect kidney function?Dr Nishchay Bhanuprakash, MD, DM Nephrology and Consultant at Kauvery Hospital, explains that your kidneys act as the body’s filtration system, working continuously to remove wastes such as urea creatine, and toxins, regulate electrolytes, and maintain fluid balance. All of these functions require adequate water. “If water intake is consistently low, the kidneys conserve fluid by producing highly concentrated urine: dark, strong-smelling, and acidic,” he notes.Chronic low water intake can create conditions that promote uric acid and calcium oxalate crystal formation, increasing the risk of kidney stones. “Habitual low water intake may be linked to a faster decline in glomerular filtration rate (GFR), the gold standard for measuring kidney function. This can gradually contribute to chronic kidney disease, especially in people with other risk factors like hypertension or diabetes,” he adds.Story continues below this adNext in line is renal perfusion or less blood reaching the kidneys. “Think of it as trying to run a complex machine on low oil; inefficient and eventually damaging. Chronic low intake isn’t just a short-term concern, it can silently pave the way toward irreversible kidney damage,” Dr. Bhanuprakash explains. If water intake is consistently low, the kidneys conserve fluid by producing highly concentrated urine: dark, strong-smelling, and acidic (source: pexels) How does low water intake affect energy, mood, or cognitive function?Even mild dehydration (1–2% body weight loss) can affect mood, alertness, memory, and concentration. “Clinical studies show increased fatigue, confusion, irritability, and headaches in dehydrated individuals. Cognitive performance in tasks involving attention, psychomotor skills, and working memory drops notably,” explains Chakrobarty.The brain is highly sensitive to hydration due to its high water content, and dehydration can impair neurotransmitter function and cerebral blood flow, reducing mental sharpness,” she further adds. Low fluid intake, thus increases perceived effort, making routine tasks feel more draining.What early warning signs indicate dangerously low hydration?Some of the clues that the body gives when water intake is dangerously low as pointed out by Dr Bhanuprakash are:Story continues below this adDark yellow or amber-colored urine and urinating less than 4 times a dayPersistent fatigue or brain fog, stemming from reduced plasma volume and less oxygen reaching muscles and the brainDry mouth, dry eyes, and chapped lipsImpairs thermoregulation and raised core temperature.Headaches because of brain tissue temporarily contracting from fluid lossIn severe cases: rapid heartbeat, low blood pressure, dizziness, and confusion, indicating hypovolemia.Also Read | Can driving dehydrated as dangerous as drunk driving?What practical tips help people stay properly hydrated?Chakraborty recommends following simple and sustainable habits:Drink water regularly throughout the day, not just when thirsty.Start your day with water and sip consistently.Use the “urine test”— pale straw-colored urine usually indicates adequate hydration.Set reminders or use hydration apps.Infuse water with citrus, mint, or berries for flavor.Carry a reusable water bottle as a visual cue.Eat hydrating foods: cucumber, watermelon, oranges, spinach.Adjust intake during exercise, illness, or hot weather.Pay attention to early signs like dry lips, fatigue, or brain fog.“These habits make hydration a lifestyle habit, not just a reactive fix,” she concludesDISCLAIMER: This article is based on information from the public domain and/or the experts we spoke to. Always consult your health practitioner before starting any routine.