Signs you’re not drinking enough water

You need to drink enough water to support your body's many functions. A part of this is recognising when your body needs you to drink more - for example, after it's lost more water on a hot day, after exercise, or following a bout of diarrhoea.

As a general rule, you should aim to drink around six to eight glasses of fluid a day¹ - and one or two glasses more if you've lost more through sweat or illness. Water should be your main source, but consuming low-fat milk and sugar-free drinks in moderation can also contribute to your daily intake.

As tea and coffee contain caffeine, you need to drink more water after caffeinated fluids to prevent dehydration. Try to avoid or limit drinks containing sugar, like fruit juices and energy drinks, as these are also dehydrating, and can lead to unhealthy weight gain and associated health problems.

Here are a few signs you're not drinking enough water:

Headaches

Not drinking enough water can lead to dehydration headaches². Some people are more prone to these headaches - athletes, for example, require more water to replenish lost fluids during physical activity. After a workout, it's essential to rehydrate by drinking enough water so that your pee turns pale or clear.

You don't have to be an athlete, or someone who exercises a lot, to be susceptible to dehydration headaches. In this case, you need to ensure you"re drinking enough water every day. A dehydration headache will generally go after an hour or so, once you've drank a few glasses of water.

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Fatigue

Tiredness - also called fatigue - tends to result from overexerting yourself or not getting enough sleep. Rehydration is the best way to remedy this situation. Water is vital for giving your body nutrients while removing waste or toxins. Not drinking enough water prevents your body from working as it should and causes various reactions - such as fatigue, altered mood, and trouble concentrating ³.

Dry mouth and bad breath

When you're not drinking enough water, you prevent proper saliva production⁴. Having a dry mouth and lips are classic signs of dehydration and a helpful reminder to drink some water. A dry mouth can also cause bad breath, as there isn't enough saliva to get rid of unwanted bacteria. This effects your ability to maintain good oral hygiene and a build up of bacteria on your tongue, teeth, or gums can cause persistent bad breath.

If you have good and regular oral hygiene, bad breath may come as a surprise - and not drinking enough water can be the reason. Increase your water intake and if your bad breath persists, and check with your dentist.

Colour and frequency of your pee

Not peeing as often, or having dark yellow coloured pee, is another common sign of dehydration⁵ - essentially, less goes in and less comes out. Your body needs plenty of water for your kidneys to flush out toxins. If you're not drinking enough, your kidneys retain more water and therefore you pee less often. Additionally, because your kidneys have less water available to flush out toxins, your pee will contain some toxins and make it dark yellow and smell stronger.

It's also possible to drink too much water - usually more than three litres a day - as this can affect the sodium levels in your blood as well as your electrolyte balance.

Digestion issues

Drinking water is essential for healthy digestion and gut health⁶, ensuring food has a smooth and hassle-free journey through your digestive tract. It also helps to soften your poo and make it easier to pass. Not drinking enough water can make poos harder and more difficult to pass, known as constipation. The signs of this are feeling bloated, gassy, and having irregular or painful bowel movements.

Muscle cramp and pain

If you're sweating a lot, or sweat out more than the amount of water you're drinking, this can cause dehydration. When your body doesn't have the volume of water to produce enough sweat, it can cause muscle cramps and joint pain. This is because you need sweat to cool you down when you're exercising or in a hot environment, and not being able to cool down will affect your muscles. Multiple glasses of water a day keep cramps and muscle pain at bay, particularly following exercise or exposure to hot conditions. A good rule is to drink until your pee is pale or clear in colour, as dark yellow pee is a sign of dehydration.

It's not just muscle that's affected by dehydration. Cartilage is the tissue that cushions and protects your bones where they meet at your joints. Up to 80% of cartilage is made up of water⁷, and drinking ensures your cartilage keeps joints lubricated. Not drinking enough damages cartilage, which in turn increases the friction between your bones and wears them down. In the long-term, this can lead to painful joints and mobility problems.

Tips for drinking enough water

Here are a few tips to make sure you get enough water every day:

Further reading

1. British Nutrition Foundation: Hydration.

2. Khorsha et al: Association of drinking water and migraine headache severity

3. Zhang et al: Effects of dehydration and rehydration on cognitive performance and mood

4. Ship et al: The relationship between dehydration and parotid salivary gland function in young and older healthy adults

5. Belasco et al: The effect of hydration on urine colour objectively evaluated

6. Vanhaecke et al: Drinking water source and intake are associated with distinct gut microbiota signatures

7. Medina et al: Systematised water content calculation in cartilage