How Much Water Should You Drink in a Day

Water is the simplest health habit in the world, and also one of the most confusing. Everyone has heard a different number. One person says eight glasses a day. Another says three litres. A third says you should drink whenever you feel thirsty and never count at all. A fourth says you must carry a bottle everywhere and sip all day. With so many different answers, it is no surprise that most people are unsure whether they are drinking too little, too much, or just the right amount.

The honest answer is that there is no single number that fits every person. Your body size, the weather where you live, how much you move, what you eat, and whether you are ill all change how much water you need. A labourer working in the sun needs far more than an office worker sitting in a cool room. A child needs less than a grown man. A person who eats a lot of fruit and soup gets more water from food than a person who eats dry bread and salty snacks. So any article that gives you one fixed number and tells you it works for everyone is not telling you the whole truth.

What this article does instead is explain how water works in your body, what the well-known guidance actually says, how to judge your own need with simple signs, and how to build a drinking habit that fits your real day. It is general information only, not personal medical advice. If you have a health condition that affects fluid, such as kidney trouble or heart trouble, or if a doctor has told you to limit or increase fluids, that personal advice comes first, and this article cannot replace it.

What Water Actually Does in Your Body

Your body is mostly water. About half to two-thirds of an adult body is water, and that water is not sitting still. It carries nutrients to your cells, carries waste away, keeps your blood flowing smoothly, helps your joints move, protects your organs, and keeps your body temperature steady. When you sweat, you lose water. When you breathe, you lose a little water. When you go to the toilet, you lose water. Every hour of every day, water is leaving your body, and drinking is how you put it back.

That is why even mild shortage makes you feel different. When you have not drunk enough, your blood becomes slightly thicker, your heart has to work a little harder to push it around, and less fluid reaches your skin, your muscles and your brain. The result is not dramatic at first. You feel tired. Your head feels heavy. Your mouth feels dry. It is harder to think clearly, and a small job feels like a big effort. Many people blame a bad night of sleep or a heavy lunch for that afternoon tiredness, when the real cause is simply that they have not drunk anything since morning.

Water also helps your digestion. Food needs fluid to move smoothly through your gut, and fibre needs water to do its job. If you eat plenty of fibre but drink very little, your digestion slows down and you feel blocked and uncomfortable. Water helps your kidneys too. Your kidneys filter your blood and remove waste in your urine, and they need enough fluid to do that work without strain. When you drink enough, your urine is pale yellow and you go to the toilet regularly. When you drink too little, your urine becomes dark yellow, strong-smelling and less frequent, which is your body’s way of saving water.

Your skin, your mouth and your eyes also show the difference. Lips become dry, skin feels tight, and your eyes feel tired when fluid is low. None of this is a disease. It is your body asking for the most basic thing it needs. Water does not cure illness, and drinking extra water does not make you superhuman. But keeping your fluid at a normal level lets every part of your body do its ordinary job properly, and that is a bigger thing than it sounds.

The Famous Eight Glasses Rule — Where It Came From

The rule most people know is eight glasses of water a day, each glass about 240 millilitres, which adds up to about two litres. It is a neat number, easy to remember, and it has been repeated so often that many people think it is a medical law. It is not. It is a rough guide, and it was never meant to be a strict rule for every person on every day.

The idea comes from old general guidance that adults need around two to two and a half litres of water a day in total, from all sources. That total includes the water in food, the water in tea, milk, soup and fruit, and plain water itself. Somewhere along the way, the total was simplified into eight glasses of plain water, and the part about food was forgotten. That is why the rule feels too much for some people and too little for others. If you eat a lot of fruit, vegetables and soup, you may need fewer glasses of plain water. If you eat mostly dry food, you may need more.

There is also a newer figure many health organisations mention. In the United States, general guidance suggests about 3.7 litres of total water a day for men and about 2.7 litres for women, again from all food and drink combined, not from plain water alone. In Europe, the figures are a little lower, about 2.5 litres for men and 2 litres for women. These are averages for healthy adults in mild weather, not orders. A smaller person needs less. A larger person needs more. A person in a hot climate needs more than a person in a cool one. The numbers are useful as a starting point, and useless if you treat them as a target you must hit exactly every day.

The real lesson of the eight glasses rule is not the number eight. It is that most people do better when they drink regularly through the day instead of waiting until they are very thirsty. Your body gives you water slowly, through food and drink, and loses it slowly, through sweat and urine. A steady supply works better than a sudden flood. Drinking a whole litre in one go because you forgot all morning does not make up for the hours you went without. It just makes you need the toilet quickly, and then you are back where you started.

How Much Most Adults Really Need

For a healthy adult living in ordinary weather and doing ordinary work, six to eight glasses of plain water a day, about 1.5 to 2 litres, is a sensible starting point, on top of the water you get from food. That is not a rule carved in stone. It is a middle point that suits many people, and you adjust it up or down by watching your body and your day.

Children need less, because their bodies are smaller. A child of four to eight years old usually needs around 1.2 litres of total fluid a day, and older children need more as they grow. Teenagers are close to adults. Older people need to be a little more careful, not because they need much less water, but because their sense of thirst becomes weaker with age. An older person can be short of fluid without feeling thirsty, which is why a regular drinking habit matters more than waiting for thirst.

Your own body weight gives you a rough guide too. A common simple estimate is about 30 to 35 millilitres of water per kilogram of body weight per day, from all sources. A person who weighs 60 kilograms would need roughly 1.8 to 2.1 litres in total. A person who weighs 80 kilograms would need roughly 2.4 to 2.8 litres. These are only estimates, and they still need adjusting for weather and activity, but they show why a small person and a large person should not aim for the same number.

The most useful way to think about it is in glasses you can see, not in litres you have to measure. A glass with breakfast, a glass mid-morning, a glass with lunch, a glass in the afternoon, a glass with dinner, and a glass in the evening adds up to six. That pattern covers the whole day without any special effort. If the day is hot, or you have been working hard, add one or two more. If the day is cool and quiet, and you have eaten soup and fruit, you may need one less. Your body is not a machine that needs an exact input. It is a living system that tells you, through thirst, urine colour and energy, whether you are close to right.

What Changes Your Need: Heat, Work, Exercise and Illness

Heat is the biggest factor. On a hot day, you sweat far more than on a cool day, and sweat is mostly water with a little salt. A person working outdoors in summer can lose a litre of sweat in an hour, and that water has to be replaced. If you wait until you feel very thirsty in the heat, you are already behind. Drinking small amounts often, before you feel desperate, works far better. Keep a bottle where you can see it, take a few sips every half hour, and do not wait for a break to drink. In hot weather, plain water is the best choice, because it replaces fluid without adding sugar.

Hard physical work changes the picture in the same way. A labourer carrying bricks, a farmer working in a field, a builder on a roof, or anyone doing heavy work for hours needs much more water than a person sitting at a desk. The work itself makes you sweat, and the sun adds to it. The same is true for exercise. A long walk in the sun, a game of cricket, a run, or an hour of hard labour all raise your need. A good habit is to drink a glass before you start, sip during the work if you can, and drink again after you finish. Waiting until the work is over and then drinking a lot at once is not as good as steady drinking through the day.

Illness also changes your need. A fever makes you sweat more and lose more fluid. Vomiting and loose motions cause a large and rapid loss of water, and replacing it matters a great deal. In those situations, small frequent sips are better than large gulps, and oral rehydration drinks, which contain a little salt and sugar, can help replace what was lost. This article cannot tell you how much to drink when you are ill, because that depends on the illness and the person, but the general principle is clear: illness raises the need, and a health professional should be asked if the loss is large or keeps going.

Pregnancy and breastfeeding raise the need as well. A woman who is breastfeeding is giving fluid to her baby, so she needs more than usual, and thirst is often stronger at that time. Older people, as mentioned earlier, may need to drink on a schedule rather than on thirst alone. And air travel, dry air conditioning, and high places can all dry you out a little more than usual, though not as much as heat and hard work. The point is simple: your need is not fixed. It moves with your day, and the person who adjusts is the person who stays comfortable.

Thirst, Urine Colour and Other Simple Signs

Your body already has a built-in guide, and it is free. Thirst is the first sign. When you feel thirsty, your body is telling you it needs fluid, and a glass of water is the right answer. Thirst is a good guide for most healthy adults in ordinary weather, but it is not perfect. By the time you feel very thirsty, you are already a little short. And in old age, or when you are very busy, you can miss the early signal. That is why drinking regularly, not only when you feel thirsty, is a better habit than waiting.

Urine colour is the second simple sign, and it is one of the most useful. Pale straw yellow means you are probably drinking enough. Dark yellow or amber means you are probably short of fluid and should drink more. Completely clear urine, all day, every day, can mean you are drinking more than you need, though one clear visit after a big glass is normal. You do not need to check obsessively. Just noticing the colour once or twice a day is enough to tell you whether you are roughly on track.

Other signs are just as plain. A dry mouth, dry lips, a headache that comes on in the afternoon, tiredness that has no other cause, and feeling dizzy when you stand up quickly can all be signs of low fluid. Constipation can also be a sign, because your gut needs water to move food along. None of these signs proves on its own that you need water, because each one can have other causes. A headache can come from lack of sleep, tiredness can come from hard work, and dizziness can come from standing up too fast. But when several of them appear together on a hot day when you have drunk very little, the message is clear enough.

There is also a simple test that many people use without realising it. If you have not passed urine for many hours, or you pass only a small amount that is very dark, you have probably not drunk enough. If you are going to the toilet every half hour and your urine is always clear, you may be drinking more than you need. The middle ground, going every few hours with pale yellow urine, is where most people feel best. You do not need an app or a chart. You need to pay attention to your own body for a few days, and the pattern will teach you more than any number on a website.

Water From Food and Other Drinks

Plain water is not the only source of fluid, and forgetting this is one of the reasons people over-count how much they need to drink. About a fifth to a quarter of your daily water usually comes from food. Fruits and vegetables are the richest sources. Cucumber, watermelon, oranges, tomatoes, lettuce and grapes are mostly water. Soup, daal, yoghurt, milk and porridge all add fluid too. A person who eats a diet rich in fruit, vegetables and soup may get close to a litre of water from food alone, which means they need fewer glasses of plain water to reach the same total.

Tea and coffee also count, despite the old idea that they dry you out. They contain caffeine, which makes you pass urine a little more, but the fluid in the drink is far more than the extra fluid you lose. A cup of tea is mostly water, and it hydrates you. The same is true for milk, which is mostly water with nutrients as well. Sweet drinks, such as fizzy drinks and sweet juices, also contain water, but they bring a lot of sugar with it, so they are a poor way to meet your fluid need. They quench thirst for a moment and then leave you wanting more, and the sugar adds calories your body does not need.

Alcohol is different. It makes you lose more water than you take in, which is one reason people wake up thirsty and headachy after drinking. It is not a source of hydration, and it should never be counted towards your daily water. The best drinks for hydration are plain water first, then unsweetened tea, milk, and watery foods. Sweet drinks are better treated as an occasional treat, not as a way to drink enough.

This also means that the eight glasses rule, if it counts only plain water, is higher than many people need, because they are already getting a good share from food and other drinks. If you eat fruit at breakfast, drink tea in the morning, eat soup or daal at lunch, and eat vegetables at dinner, you may only need four or five glasses of plain water to reach a healthy total. If you eat mostly dry food, bread, rice and fried snacks, with little fruit or soup, you may need seven or eight glasses. The food on your plate changes the number in your glass, and a person who understands that will never be confused by a single fixed target again.

Too Much Water Is Also Possible

Most people worry about drinking too little, and that worry is usually right, because too little is far more common than too much. But drinking far too much water in a short time can also cause problems, and it is honest to say so. Your kidneys can remove about a litre of water an hour, and if you drink much more than that for several hours, the salt level in your blood can fall too low. This is rare, and it almost never happens from normal drinking. It happens when someone drinks several litres very quickly, for example during a long race, or as part of a dare, or because they believe more water is always better.

The signs of drinking too much are feeling sick, a headache, confusion, and swelling in the hands or feet, and needing the toilet constantly with completely clear urine. If you ever feel like that after drinking a very large amount, stop drinking and ask for medical help. Again, this is rare. A person who drinks six to eight glasses spread through the day is not at risk. A person who drinks a glass every hour is not at risk. The risk comes from forcing litres down in a short time, and from ignoring what your body is telling you.

The other problem with too much water is simpler and more common: it disturbs your sleep. Drinking a large glass just before bed means you will wake up in the night to use the toilet, and broken sleep makes the next day harder. A better habit is to drink most of your water during the day and slow down in the last hour or two before bed. A small sip if you are thirsty is fine, but a full bottle at bedtime is not a good idea.

There is also a quiet myth that drinking extra water will clean your body, clear your skin, or make you lose weight on its own. Water does not work like that. It helps your kidneys do their job, and it helps you feel full if you drink a glass before a meal instead of eating more, but it is not a treatment. Clear skin comes from many things, including sleep, food, and skin care, not from water alone. Weight loss comes from eating less and moving more over time, not from drinking litres of water. Water is essential, but it is not magic, and expecting magic from it only leads to disappointment.

Building a Simple Daily Water Habit

Knowing how much water you need is only half the job. The other half is making drinking easy, because a habit you have to think about every time will not last. The simplest way is to tie drinking to things you already do. Keep a glass or a bottle where you can see it. Put it on your work table, beside your bed in the morning, or on the kitchen counter. Water you can see is water you will drink. Water hidden in a cupboard is water you will forget.

Start the day with a glass. After a night of sleep, you have gone eight hours without drinking, and your body is a little dry. A glass of water in the morning, before or with breakfast, is an easy win. Then drink a glass with each meal. That alone gives you three glasses without any extra effort. Add one in the middle of the morning and one in the afternoon, and you are at five. Add one in the evening, and you are at six. That is a full day’s drinking, built from moments you already have.

Carrying a bottle helps, especially if you work outside or travel. Choose a bottle you like, fill it in the morning, and refill it once during the day. A one-litre bottle, filled twice, is two litres. You can see your progress without counting glasses. If you do not like plain water, add a slice of lemon, a few mint leaves, or a slice of cucumber. It changes the taste without adding sugar, and it makes the habit more pleasant. Cold water in summer and room-temperature water in winter also help, because you will drink more of what feels good.

Children need the same simple system. Give a child a small bottle for school, remind them to drink at breaks, and offer water with meals instead of sweet drinks. Older people may need a reminder too, because thirst fades with age. A glass on the table at each meal, and a small glass in the afternoon, is a kind and simple way to help. And if you take medicine that makes you pass urine more often, or if you have been told to drink more or less for a medical reason, follow that advice and ask your doctor how to fit it into your day.

The last point about habit is the most important: do not make it a punishment. If you miss a glass, nothing bad happens. Drink the next one. If you drink a sweet drink at a wedding, enjoy it and drink water later. A good habit is not a perfect record. It is a pattern that holds most days, and that you return to without guilt when it slips. Water is the easiest part of looking after your health, and it should feel easy, not stressful.

My Take:

If you ask me how much water a person should drink in a day, I will not give you a single number and walk away, because I think that is the reason so many people are confused. The honest answer is that six to eight glasses of plain water suits most adults on an ordinary day, on top of the water they get from food, and then you adjust it. Hot day, drink more. Hard work, drink more. Cool quiet day, maybe a little less. That is not a vague answer. It is the true answer, and I think people deserve the true answer instead of a magic number that pretends every body and every day is the same.

I think the eight glasses rule has done more harm than good, not because it is a bad starting point, but because it was repeated as a law. I have seen people force themselves to drink glass after glass, counting on their fingers, feeling guilty when they reach only five, and then drinking a litre at night to catch up. That is not health. That is anxiety with a glass in your hand. Water should be the easiest thing in your day, not a test you can fail. If you drink regularly, eat fruit and vegetables, and your urine is pale yellow, you are doing fine, whether the count is five glasses or eight.

I also think we talk about water as if it is a medicine, and that is a mistake. Water does not cure disease, it does not clean your blood on its own, and it does not make you lose weight by itself. What it does is simpler and more important: it lets your body do its normal work. It lets your blood flow, your digestion move, your kidneys filter, and your brain think clearly. When you are short of water, all of those ordinary jobs get a little harder, and you feel it as tiredness, headache and dryness. When you have enough, you do not feel anything special. You just feel normal. And normal is underrated. Most of health is not about feeling amazing. It is about feeling normal, day after day, and water is one of the cheapest ways to stay normal.

There is a reason I care about this topic, and it is about work. I think about people who work in the sun, who carry heavy loads, who spend hours on a roof or in a field, and who often drink very little until the work is done. I think about a labourer who leaves home with no bottle, works all morning, and only drinks at lunch. By then he is already dry, tired and headachy, and he thinks it is the heat or the work itself. It is the heat and the work, but it is also the missing water. A bottle of water is the cheapest tool a worker can carry, cheaper than any medicine, and it makes the whole day easier. If you work in the sun, please carry water. Do not wait for thirst. Sip through the morning, sip through the afternoon, and you will feel the difference by evening.

I also want to say something about children, because I think we teach them the wrong habit early. We give children sweet drinks because they ask for them, and we give them water only when they are ill or thirsty. Then we wonder why they do not like water. A child who grows up drinking water with meals, carrying a small bottle to school, and eating fruit every day will not need to be told to drink water as an adult. It will be normal to them. A child who grows up on sweet drinks will have to learn the habit later, and learning later is always harder. If you are a parent, the simplest gift you can give your child is a bottle of water and a habit of drinking it. It costs almost nothing, and it lasts a lifetime.

I am also honest about the limits of my view. I am not a doctor, and this article is not personal advice. If a doctor has told you to limit water because of your kidneys or your heart, follow the doctor, not this article. If you are ill and losing a lot of fluid, ask a health professional how much to drink, because the right amount in that situation depends on your illness. General guidance is for general days. Your own body and your own doctor matter more than any article, including this one. I would rather say that plainly than pretend one article can cover every person.

Another thing I believe is that we make health too complicated. People buy special bottles, download apps that remind them to drink, and buy water with added vitamins and minerals, as if plain water is not good enough. Plain water is good enough. It has been good enough for every generation before us. A clean glass of water, a bottle you refill, and a habit of drinking through the day will do more than any expensive product. The companies that sell you special water are not selling you health. They are selling you worry, in a bottle. I would rather you spend that money on fruit, or on a good bottle you can reuse for years.

I also think the timing of water matters more than the total. Drinking a litre in the morning and nothing for the rest of the day is not the same as drinking a glass every few hours. Your body loses water steadily, so it needs water steadily. The people who feel best are usually the ones who drink a little, often. A glass with breakfast, a glass mid-morning, a glass with lunch, a glass in the afternoon, a glass with dinner. That is the whole method. It is not clever, it is not new, and it works. I like methods like that. They are the ones people actually keep.

I want to be honest about thirst as well. Thirst is a good guide, and you should listen to it, but do not wait for it as your only signal. By the time you are very thirsty on a hot day, you are already behind, and catching up takes time. Older people feel thirst less, busy people ignore it, and workers in the sun can miss it entirely. So drink on a pattern, not only on a feeling. The pattern protects you when the feeling is quiet. And check your urine colour once a day. Pale yellow is good. Dark yellow means drink more. It is a simple check, it costs nothing, and it tells you more than a counting app ever will.

If I had to give one piece of advice about water, it would be this: keep it simple, keep it steady, and keep it visible. Keep a bottle where you can see it. Drink with meals. Drink a little more when it is hot or when you work hard. Drink less in the last hour before bed so you sleep well. Eat fruit and vegetables, because they are water too. And do not feel guilty about the days you drink less. Just drink the next glass. Health is not built in one perfect day. It is built from small, ordinary habits that you repeat without thinking, and a glass of water is the smallest and easiest of them all.

I think that is the real lesson of water. It is not a special drink, it is not a treatment, and it is not a challenge. It is the most ordinary thing in the world, and your body needs it every day, in a steady, quiet way. Give it what it needs, and it will do its work without fuss. Ignore it, and it will remind you with tiredness, headache and thirst. Listen to those reminders, keep a bottle near you, and let water be the easy part of your day. In my view, that is enough, and enough is exactly what good health looks like.

I also think about food when I think about water, because the two are never separate. A person who eats fruit, vegetables, soup and daal is drinking without realising it, and that person will feel better than a person who eats only dry, salty food and then tries to make up for it with glass after glass of water. Food and water work together. A plate with fruit and vegetables is a plate that hydrates you. A plate with only bread and fried snacks is a plate that leaves you dry. If you want to drink less water and still feel well, eat wetter food. It sounds too simple, but simple is usually right. A watermelon in summer, an orange after lunch, a bowl of soup in winter, these are not just foods. They are water in a form your body enjoys, and they make the whole business of drinking easier.

There is another point I want to make, and it is about money. Water is free, or almost free, in most homes, and that is a gift we take for granted. People spend money on sweet drinks, on energy drinks, on flavoured water in fancy bottles, and then they say they cannot afford to look after their health. A glass of clean water costs nothing, a bottle you refill costs nothing after the first day, and a habit of drinking water costs nothing at all. If you are short of money, water is the one healthy habit that asks nothing from you. It does not ask for a gym, a diet plan, or a special product. It asks for a tap, a glass, and a little attention. I think we should be grateful for that, and I think we should use it.

I also want to speak plainly about the habit of carrying water. I know it feels like a small thing, almost silly, to carry a bottle everywhere. But the people who carry a bottle drink more, and the people who drink more feel better, and that is the end of the story. A bottle on your desk, a bottle in your bag, a bottle beside your bed, these are not signs of fussiness. They are signs that you have made drinking easy for yourself. The hardest part of any habit is remembering to do it, and a bottle you can see is a reminder that never runs out of battery. Put it where you will see it, fill it in the morning, and let it do the remembering for you.

Finally, I want to say that I do not expect you to be perfect at this. Some days you will drink well, and some days you will forget, and you will get to the evening with a headache and realise you have had almost nothing since morning. That happens to everyone, including me. The answer is not guilt. The answer is a glass of water, and then a better day tomorrow. Health is not a test you pass once. It is a pattern you return to, again and again, without drama. Drink a glass now, keep a bottle near you tomorrow, eat some fruit, and let the habit grow quietly. That is my view, and I think it is a view worth keeping, because it is honest, it is simple, and it works for real people on real days, not just for people in books. If you remember only one thing from this whole article, let it be this: drink regularly, watch for pale yellow urine, and trust your own body more than any number you read online. A glass with each meal, a bottle you can see, a little more on hot days, and a little less before bed, that is the whole habit, and it is enough for most people, most days. You do not need a special bottle, a special app, or a special kind of water. You need a clean glass, a tap you trust, and a habit you can keep without thinking about it. Start tomorrow morning, keep it simple, and let the small habit do its quiet work, day after day, without any fuss at all.

Frequently Asked Questions

Why does how much water should you drink in a day happen in everyday life?

People ask this question in everyday life because water is part of every day, and the advice they hear is confusing. One source says eight glasses, another says three litres, and a third says just drink when you are thirsty. The question comes up again on hot days, during hard work, and when someone feels tired or gets a headache and wonders whether low fluid is the cause. It is a normal question, not a rare one, because drinking is something every person does, and everyone wants to know whether they are doing it right.

Is how much water should you drink in a day something most people experience?

Yes, almost everyone thinks about this at some point. Water and drinking are tied to ordinary daily life, not to anything rare. A worker in the sun, a student in a hot classroom, a mother cooking in a warm kitchen, and an older person who forgets to drink all face the same question in different ways. People experience it differently, so comparing your own days with someone else’s is rarely useful. What matters is your own pattern, your own weather, and your own work.

How long does how much water should you drink in a day usually take to settle into a routine?

There is no fixed number of days, because every routine is different. Most people find that a small, steady change needs a few weeks before it feels natural. Keeping a bottle where you can see it, drinking a glass with each meal, and drinking a little more on hot days will start to feel automatic after two or three weeks. The useful approach is to keep the change small, repeat it daily, and judge it after a fair stretch of time, not after a single day.

What simple daily habits help with how much water should you drink in a day?

Simple habits help more than dramatic changes. Keep a bottle where you can see it, drink a glass with breakfast, lunch and dinner, and add a glass in the middle of the morning and the afternoon. Eat fruit, vegetables and soup, because they add water too. Drink a little more on hot days and during hard work, and drink less in the last hour before bed so your sleep is not disturbed. Pick one habit, keep it small, and add another only when the first one feels easy.

Can how much water should you drink in a day change with the seasons?

Yes, it changes a lot with the seasons. In summer, heat and sweat raise your need, sometimes by a litre or more a day. In winter, you sweat less, but heated rooms and dry air can still dry you out, and people often forget to drink because they do not feel hot. In the rainy season, humidity and changes in routine can change how thirsty you feel. A habit that works in one season may need a small adjustment in another, usually a change in timing or amount, not a whole new routine.

When should I ask a health professional about how much water should you drink in a day?

You should ask a qualified health professional if drinking keeps worrying you, if you have been told to limit or increase fluids because of a kidney, heart or other condition, or if you are losing a lot of fluid through fever, vomiting or loose motions and cannot keep up. Also ask if you feel dizzy, confused, or very unwell after drinking a large amount, or if a change in thirst or urination is sudden and unexplained. This article is general information only and cannot judge an individual situation.