# How much water should I drink a day? What EFSA, the IOM and ICMR-NIN actually say

Source: https://spolvero.design/articles/how-much-water-should-i-drink-a-day/
Updated: 2026-10-06
Tool: https://spolvero.design/enough/

> Most adults need roughly 1.5 to 3 litres of drinks a day. EFSA's figure is 2.0 litres of total water for women and 2.5 for men, and about a quarter of that comes from food, which leaves about 1.5 and 1.9 litres to drink. The US IOM's higher figures leave about 2.2 and 3.0 litres. India's ICMR-NIN gives drinks directly, by body weight.

Ask how much water to drink and you will usually hear "eight glasses" or "two litres". Both are round numbers that nobody official ever quite said. The published guidance is more useful once you know one thing about it: the big figures are for **total water**, and part of that you eat.

## The three standards, side by side

Three bodies publish an adequate intake that a careful app can cite:

| Standard | Women | Men | What the figure covers |
| --- | --- | --- | --- |
| EFSA (2010) | 2.0 L | 2.5 L | Total water, from drinks and food |
| US Institute of Medicine (2004/5) | 2.7 L | 3.7 L | Total water, about 80% from drinks |
| ICMR-NIN (2020) | 27 to 52 ml per kg | 32 to 58 ml per kg | Drinks only, by activity |

These are figures for healthy adults on an ordinary day. They are population guidelines, not a prescription for you.

## Take off the share you eat

Fruit, vegetables, rice, dal and soup all carry water. EFSA says food supplies 20 to 30 percent of total water. The IOM says about 80 percent arrives as drinks, so about 20 percent comes from food.

Subtract that share and the amount to actually pour is noticeably lower:

| Standard | Women | Men |
| --- | --- | --- |
| EFSA, less 25% from food | 1.5 L | about 1.9 L |
| US IOM, less 20% from food | about 2.2 L | about 3.0 L |

That is why a careful target often looks smaller than the number on a poster. The poster gave you total water and then asked you to drink all of it.

## India's figure works differently

ICMR-NIN publishes no total-water figure. It goes straight to the water you need **from drinks**, per kilogram of body weight, and it scales with how hard the day is. Nothing comes off it for food, because food is already accounted for.

Some worked examples:

| Person | Activity | Per kg | Drinks a day |
| --- | --- | --- | --- |
| Woman, 55 kg | Mostly sitting | 27 ml | about 1.5 L |
| Woman, 55 kg | Physical work most of the day | 52 ml | about 2.9 L |
| Man, 70 kg | Mostly sitting | 32 ml | about 2.2 L |
| Man, 70 kg | Physical work most of the day | 58 ml | about 4.1 L |

The spread is the point. A desk job and a day of labour in the heat are not the same day, and one number cannot cover both.

## What moves your number on a given day

The standards describe an ordinary day. Your real need goes up with:

- **Heat.** You sweat more, even sitting still.
- **Exercise.** A long session or a hard physical day adds to what you lose.
- **Fever.** A raised temperature increases water loss.

Body size matters too. EFSA and the IOM publish one figure per sex, with no per-kilogram adjustment for adults, so any app that moves the number for your weight is making its own estimate. It should say so.

## Is there such a thing as too much?

Yes. Drinking far more than you lose, especially in a short time, dilutes the sodium in your blood. This is called hyponatremia, and it is most often seen in long endurance events where people drink heavily and keep going for hours. For most people on most days it is not a risk, but "more is always better" is not true.

That is the idea behind [Enough](/enough/), our water tracker for Android. Alongside your target it shows a ceiling at 1.6 times your drinking target. The app labels that ceiling as a conservative rule of thumb, not a published limit, because no standard gives one. Pass it and nothing is blocked: you are told, not stopped.

## Does coffee count?

It does. A 2016 trial found coffee, tea, juice and soft drinks hydrate no differently from water, and milk was retained better. The details, and what the trial did not test, are in [does coffee count as water intake?](/articles/does-coffee-count-as-water-intake/)

## How Enough works this out

[Enough](/enough/) asks which standard you want (EFSA, the US IOM or ICMR-NIN, with ICMR-NIN as the default in India), your sex and your weight, and for ICMR-NIN how active your day is. It then shows every step on screen: the total-water figure, the food share it took off, and any adjustment it made for your weight. The weight adjustment is its own, capped at 10 percent of the target, and you can turn it off.

If you think the number is wrong, set your own. The standard's suggestion stays beside yours so you can see the difference. Enough has no account and keeps your record on your phone.

If you have a kidney, heart or liver condition, or you are pregnant, the figure from your clinician is the one to follow, not a population guideline or an app.

## Questions

### How much water should a woman drink a day?

By EFSA, about 1.5 litres of drinks: 2.0 litres of total water, less the quarter that food provides. By the US IOM, about 2.2 litres: 2.7 litres of total water, less a fifth from food. ICMR-NIN gives 27 to 52 ml per kg of body weight from drinks, from sedentary to heavy work.

### How much water should a man drink a day?

By EFSA, about 1.9 litres of drinks: 2.5 litres of total water less a quarter from food. By the US IOM, about 3.0 litres: 3.7 litres less a fifth. ICMR-NIN gives 32 to 58 ml per kg of body weight from drinks, depending on how active the day is.

### Is eight glasses a day right?

It is a rough rule, not a standard. None of EFSA, the US IOM or ICMR-NIN states it. Eight 250 ml glasses is 2 litres, which is above EFSA's drink figure for most women and below the IOM's for most men.

### Does the water in food count?

Yes. EFSA and the IOM publish total water, which includes food moisture. EFSA puts food at 20 to 30 percent of it and the IOM at about 20 percent, so the amount you need to drink is lower than the headline figure.

### Can I drink too much water?

Yes. Drinking far more than you lose, especially quickly, can dilute the sodium in your blood. Enough shows a ceiling at 1.6 times your drinking target, labelled as a conservative rule of thumb rather than a published limit.