Summer hydration: how much water per hour at the beach, by NHS guidance

Does a single glass of water in the morning settle the question of hydration for the whole day? Not in a Serbian summer.

Once the thermometer climbs past 30 degrees the body loses fluid through sweat faster than it can replace it. The British NHS has, in recent years, published seasonal guidance that applies to our climate just as well.

What the NHS actually recommends

The baseline NHS guidance is six to eight glasses of fluid a day for an adult, which works out at roughly 1.6 to 2 litres. That figure assumes temperate weather and ordinary daily activity.

In high temperatures the body loses more fluid, so the intake needs to rise above the standard six to eight glasses, particularly during physical activity and prolonged sun exposure.

For summer conditions, add about 500 millilitres per hour spent in direct sun. A morning-to-afternoon stretch at the beach calls for an extra 1.5 to 2 litres on top of the baseline.

What counts as fluid

Water is not the only source. The NHS counts towards your daily intake:

• unsweetened tea and coffee (up to three cups, caffeine still has a mild diuretic effect)
• water from fruit and vegetables (watermelon, cucumber, oranges)
• milk and plant milks
• soups and broths
• low-sodium mineral water

Alcohol and sugary fizzy drinks do not count as fluid, since they speed up water loss. A beer in the sun is a double mistake: it dehydrates and overloads the heart.

How to spot dehydration early

The first signals are subtle. The NHS suggests checking:

• urine colour, a dark yellow means drink water now
• a dry mouth and tongue that do not respond to chewing
• a late-afternoon headache after a day in the sun
• dizziness when you stand up quickly
• less sweat despite continued heat, which is a more serious sign

A severe case shows very dark urine, a fast pulse and confusion. That is a case for medical help.

Special groups with different needs

Different life stages call for different maths in the NHS guidance.

• Children aged 4 to 8, about 1.2 litres a day, with 30 per cent more in summer
• Teenagers, around 1.7 to 2 litres a day, with 40 per cent more in summer
• Adult women, 1.6 litres, rising to 2.5 to 3 litres on hot days
• Adult men, 2 litres, rising to 3 to 3.5 litres
• Pregnant women, around 2.3 litres a day regardless of season
• Breastfeeding women, 2.7 to 3 litres a day
• Adults over 65, at least 1.6 litres, paired with a two-hourly prompt

Older adults have a reduced thirst signal. The NHS suggests a routine schedule every two hours rather than waiting for the body to ask.

A practical plan for a day at the beach

Before you leave, drink two glasses of water at home. Bring a bottle of at least a litre and top it up in the afternoon.

Small sips every 15 minutes work better than large amounts every couple of hours. The body absorbs evenly and you avoid the heavy stomach feeling.

If you plan a swim or a long walk along the shoreline, add a small electrolyte sachet. Plain water after two hours of sweat loss does not replace everything the body has lost.

What about children in the car

A road trip to the coast with small children calls for extra care. Air-conditioning in the car dries the air, so children dehydrate even out of the sun.

A break every 90 minutes with a glass of water and a short walk solves 90 per cent of the problem. Sugary juices and fizzy drinks make a child thirsty again within half an hour.

Which bottle works best for tracking your daily intake? Do you use a phone reminder or another system? Tell us in the comments.