How much water per day? Calculate your amount

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How much water per day do you really need?

For a healthy adult, the advice comes out at 1.5 to 2 litres of drinking per day. That's the guideline used by the Voedingscentrum, and it covers all your drinks added together: water, tea, coffee, milk and plant-based alternatives all count. So you don't need to get through another two litres of plain water on top of your four cups of tea.

The well-known "eight glasses of water" is a rule of thumb, not a law. There are two ways of looking at your water needs, and they're often mixed up.

That difference explains why you see two figures online. If someone talks about 2 litres, it's usually about drinking. If someone talks about 2.5 litres, the moisture from your food is often already included. An apple is on average 85% water and a carrot 90%, so it adds up faster than you'd think.

Your body is also a good accountant. In adults who move little, metabolism alone produces 250 to 350 millilitres of water per day, and in those who are quite active that rises to 600 millilitres. At the same time, you lose 1 to 2 litres a day through urine, around 450 millilitres through your skin and 250 to 350 millilitres through your breath. That balance is exactly what the drinking advice is based on.

Per day for men, women, children and the elderly

Men need more on average than women, simply because they're on average larger and have more muscle mass. An adult woman's body is 50% to 55% water, a man's is on average 60%. Below are the EFSA reference values for total water intake, alongside the Voedingscentrum's minimum drinking advice.

Older adults: same advice, bigger risk

For people over 70, the same recommended amount applies as for other adults. Yet the group is more vulnerable, because the thirst sensation weakens with age, appetite decreases and the kidneys work slightly less well. The result: drinking less without noticing it, with a higher risk of dehydration and urinary tract infections. Fixed drinking moments work better here than waiting for thirst.

Children and babies

Babies up to 6 months need 100 to 190 millilitres of water per kilogram of body weight per day, which for a 5-kilo baby works out at 500 to 950 millilitres. That comes entirely from breast milk or formula. From 6 months to 1 year it's about 800 millilitres to 1 litre. If you use tap water for the bottle, let the cold tap run for a moment first. Why that matters is explained in our piece on drinking hot tap water.

Calculate it yourself based on your body weight

If you want to make it more personal than a general recommendation, the usual calculation is 30 to 35 millilitres per kilogram of body weight for total water intake. If you use 33 millilitres, you arrive at these figures.

A calculation like this is a starting point, not medical advice. If you use medication that affects your fluid balance, or have a heart, kidney or liver condition, discuss it with your GP. The same applies if you follow a strict fluid-restricted diet.

When you need more

Four situations clearly increase your need, and in all four it's about fluid loss you need to replenish.

• During intense exercise you can lose 1 to 2 litres of water per hour through sweat, and exactly how much depends on the temperature, your clothing and whether it's windy.
• On a really hot day, the Voedingscentrum advises adults to drink at least 2 litres, but no more than 3 litres a day.
• With diarrhoea, vomiting or fever you lose a lot of fluid, and the advice then is 2 litres or more, in small sips spread over the day.
• If you're pregnant or breastfeeding, the advice is at least 1.6 and 1.8 litres of drinking per day respectively, because you eat more and give up more fluid.

What isn't true: the idea that coffee dehydrates you. Caffeine briefly speeds up fluid loss, but you don't lose more fluid with it than with other drinks. Coffee simply counts. The idea that drinking extra water "detoxifies" your body doesn't hold up either: there's no evidence that drinking more than you need has a cleansing effect. Your liver, kidneys and intestines already do that job.

Can you drink too much water?

Yes, but it's rare. Your kidneys can excrete around 0.7 to 1 litre of water per hour. If you take in an extreme amount of water in a short time, the sodium level in your blood can become too low. This is called water intoxication and can, in severe cases, lead to fluid on the brain. Well-known examples mostly come from endurance sport, where someone drinks an enormous amount in a short time after a long race.

For the average person in the Netherlands the limit is practical: the Voedingscentrum advises drinking no more than 3 litres a day, even on hot or sick days. Older adults are at slightly higher risk, because their kidneys often work less well. So drink spread out over the day rather than a litre all at once.

How to tell if you're drinking enough

You don't need an app. The Voedingscentrum names the amount of urine as the clearest signal: if you're a healthy adult urinating around 100 millilitres per hour, your fluid balance is fine. More than 300 millilitres per hour means you're drinking too much, less than 30 millilitres per hour that you're not getting enough.

Colour is a second clue: light yellow is fine, dark yellow can mean you need to drink more, and urine that looks like water all day points to more than necessary. Do note that food and medication also affect the colour.

Symptoms of drinking too little are a dry mouth, headache, dizziness, fatigue and poor concentration. With severe fluid deficiency, cramps, low blood pressure and heart palpitations are added to that. If you notice such complaints regularly while drinking enough, raise it with your GP.

Not just how much, but also what you drink

This is where almost every article on this topic stops, and this is exactly where the interesting part begins. If you put 2 litres through your body every day, you drink around 730 litres a year. Everything that's in those 730 litres therefore passes through 365 times.

Dutch tap water is good, and it's absurdly cheap. According to Vewin, the weighted average drinking water rate in 2026 is around €2.71 per cubic metre including taxes. Those 730 litres therefore cost you around €2.00 a year. Anyone who wants to see the full calculation will find it in our explanation of what a cubic metre of water costs.

Still, there's room for improvement. RIVM concludes that people in the Netherlands take in too much PFAS, and that tap water made from surface water usually contains more PFAS than the target value RIVM proposes. The institute considers it responsible to keep drinking tap water, but does advise the government to reduce exposure. On top of that, the last stretch of pipe, from the water meter to your tap, is no longer the responsibility of your water company but of the owner of the building. In older buildings that can mean copper or lead.

At PureFilter we see that customers switch for exactly that reason: not because they're afraid of their tap water, but because they want to make the most of 730 litres a year. If you first want to know what techniques exist, our page on how water filters work and which types exist explains that step by step.

Why minerals belong in it

Many filters remove everything, including the calcium and magnesium you actually want to keep. That's also the criticism of reverse osmosis and of most filter jugs, something we discuss in detail in our review of Brita filters. The PureFilter Mineral+ does it the other way round: first purify through five steps, then mineralise with Swedish Mineral Rock™, which gives calcium, magnesium and potassium back. The result is water that tastes softer and fuller, and that you drink more easily in larger quantities. More about the role of these substances is in our piece on minerals in drinking water.

Buying advice: when a filter pays off

A filter isn't a must to hit your two litres. It pays off especially if one of these applies to you.

• You drink a lot of water, because from around 2 litres a day per person you notice the taste difference daily, not just occasionally.
• You currently buy bottles, which already puts you at €250 or more a year, versus less than one cent per litre for a replacement filter.
• You live in an older building, where copper or lead pipes fall outside your water company's control.
• You use tap water for baby formula, coffee or tea, where both purity and taste count double.

If you'd rather have an overview of all the types side by side, our comparison of the best water filter will help. If you have a boiling water tap, it's good to know that it doesn't filter the water; how to combine the two is covered on our page about a water filter with a Quooker. And if you just want to see what's available, take a look at our water filters for household use.

Frequently asked questions

Conclusion

On the question of how much water per day you should drink, the honest answer is: 1.5 to 2 litres of drinking for most adults, 2 to 2.5 litres of total water intake according to EFSA, and more with sport, hot weather, illness or pregnancy. If you calculate based on your weight, 30 to 35 millilitres per kilo gets you in the same range. Above 3 litres a day has no proven benefit.

The more interesting question is what's in those 730 litres a year. Dutch tap water is good and costs you around €2.00 a year for that amount, but RIVM still sees PFAS in water made from surface water, and the pipes in your own home fall outside your water company's control. An under-sink filter that both purifies and mineralises covers exactly that part, for less than one cent per litre. Water as it's meant to be, every day again.