Drinking habits

Not drinking enough water: how to recognise the symptoms

The symptoms of not drinking enough water are rarely dramatic, which is exactly why they are so easily overlooked. The body signals a fluid deficit through subtle cues: thirst, tiredness, darker urine, fading concentration. It pays to know these signals, and it pays even more to build drinking habits that stop a deficit from arising in the first place.

Updated August 2026 · 6 min read

Which symptoms show that you are not drinking enough water?

Fluid balance is one of the most tightly regulated systems in the body. When it is disturbed, the organism first responds with unspecific signals that are easy to miss. The kidneys then retain water and concentrate the urine. The simple self-check via urine colour is based on exactly this response. Typical early signs include:

• Thirst and a dry mouth: thirst is a late signal that often only appears once a slight deficit exists.
• Dark, concentrated urine and less frequent trips to the toilet: pale, straw-yellow urine serves as a rough everyday indicator of adequate fluid intake.
• Fading concentration and tiredness: even small fluid deficits can affect attention and performance.
• Headaches: many people notice a dull pressure in the head when they drink little, and it often eases again after drinking.
• Dry lips and dry skin as outwardly visible clues.

Temperature, activity and diet determine how quickly a deficit makes itself felt. On a cool day at the office it takes longer than in summer heat, but the signals remain the same.

None of these signs proves a fluid deficit on its own; tiredness or headaches can have many causes. Taken together, and coinciding with a low drinking volume, they are a useful prompt to review your drinking habits.

Why does the sensation of thirst fade with age?

Thirst regulation changes as we grow older: with a comparable fluid deficit, older people often feel considerably less thirst than younger ones. The change is well documented, and it is why, in later life, drinking by fixed habit works better than waiting for thirst. The fading sensation itself tends to go unnoticed: nothing seems to be missing, and so you drink less.

Added to this, the body's water content decreases with age, and some medications affect fluid balance too. Anyone caring for older relatives can help with simple means – a clearly visible carafe, a glass of water with every meal, or friendly reminders. Drinks people actually enjoy get drunk far more readily than those that are merely “sensible”.

In which everyday situations do we drink too little?

A fluid deficit usually builds up through many small omissions over the course of the day. A few situations crop up again and again.

At the office, the culprit is usually distraction: when you are working with concentration, thirst signals are easily missed, and one hour without drinking quickly turns into half a day. Dry, air-conditioned air raises losses through breathing as well, without any visible sweating.

Heat is a different matter. The need rises markedly, because the body cools itself through sweat and the losses add up faster than thirst can keep pace. On hot days it pays to start drinking in the morning and to spread the amount evenly across the day, because an evening catch-up rarely closes the gap. To see what this means for your amount, try the water intake calculator for hot days.

Sport is the third classic: how much you lose is a question of intensity and duration, and of the temperature you train in. A practical rule of thumb: drink before training, during longer sessions also while training, and replace the losses afterwards. If you want to know it precisely, weigh yourself before and after training – the difference in weight roughly corresponds to the fluid lost. The water intake calculator gives a starting point for training days.

How much should you drink each day?

The European Food Safety Authority (EFSA) gives as a guide value a total water intake of around 2.0 litres per day for women and 2.5 litres for men; part of this is taken in through solid food, for instance water-rich foods such as fruit, vegetables or soups. These values apply to healthy adults in a temperate climate with average activity. As a pure drinking amount, that leaves around 1.5 to 2 litres per day for most adults. Individual needs depend on body weight, activity, temperature and diet. For personal guidance, try our water intake calculator.

Incidentally, more is not automatically better: drinking too much water can also put a strain on the body. The aim is a steady intake adapted to your own daily life.

Which routines help you drink enough?

Drinking works most reliably when fixed habits do the work, attached to routines you already have. Some examples that are easy to keep up:

• A glass of water straight after getting up: the night is the longest drinking pause of the day.
• A filled carafe or bottle in plain view on your desk: what you can see, you drink.
• A glass of water alongside every coffee or tea.
• Link drinking to fixed occasions: before every meal, say, or on every trip to the kitchen.
• On hot days and before sport, drink ahead of time.
• Choose a water you genuinely enjoy: taste is the most underrated factor in how much you drink.

That said, not every routine suits every daily life. Two or three of them, applied consistently, are usually enough to noticeably increase your daily intake.

Persistent tiredness, headaches or dizziness can have many causes and cannot be explained by drinking volume alone. If symptoms persist or you are unsure (with older people, with fever or with heavy fluid loss, for instance), seek medical advice.

Perhaps the simplest routine of all is a water you actually enjoy. Piz Sardona is a naturally alkaline mineral water with a pH of 8.0 from the Castels spring in Mels: its catchment area lies at over 2,000 metres above sea level in the Sardona Alps, at the UNESCO World Heritage Tectonic Arena Sardona, and the water filters through layers of rock and stone for around twelve years before it is collected. More about our water.

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