“Water, water everywhere and not a drop to drink,” wrote Samuel Taylor Coleridge in his 19th-century poem The Rime of the Ancient Mariner . The speaker, a sailor on a becalmed ship, is surrounded by salt water that he cannot drink. The moral of the lengthy tale is to appreciate all forms of life. Water is crucial to nearly all life forms, particularly human life, but fresh water is a dwindling resource. World Water Day, an annual United Nations observance day that falls on 22 March, celebrates fresh water and raises awareness of the 2 billion people living without access to safe water. The most important resource on the planet, water covers 70 per cent of the globe. It also makes up about 60 per cent of the human body. The brain and heart are composed of 73 per cent water, the lungs about 83 per cent, the skin 64 per cent, muscles and kidneys 79 per cent – and bones 31 per cent. This is why drinking water plays a key role in keeping our organs and bodily systems functioning smoothly. Michelle Lau of Hong Kong’s Nutrilicious, a nutrition consultancy and communications company, says adults need to drink eight to 10 glasses a day to maintain healthy hydration. Beyond sustaining life, water has multiple health benefits. 9 intermittent fasting errors, from eating too little to exercising too much Exercising in water, for example, has many benefits. Swimming is an excellent form of cardiovascular exercise. And workouts in water are low impact , which keeps joints safe, says physiotherapist Wendy Lam at Hong Kong’s holistic health clinic Balance Health. Its natural turbulence “provides resistance in all planes and directions which challenges our strength, balance and core control in a new way” Lam says. The movement of water also has a massaging effect. Exercise and rehabilitation scientist Sven Hoekstra at Loughborough University in the UK notes that exercising in hot water may be especially good for us. It increases the concentration of an important marker for brain health that you don’t get from simply soaking in a hot bath. Lam explains: “Heat increases the skin and joint temperature, improves blood circulation, enhances muscle relaxation and decreases joint stiffness. The metabolic rate ... will also increase [and] warm water makes the muscle tissue stretch more easily. Heat also increases oxygen uptake and accelerates tissue healing.” Many people also believe in the benefits of bathing in cold water. Ice baths and cold showers seem to be trending now. Lam says: “Cold reduces pain, decreases swelling and blocks nerve impulses to the joint. Cold water immersion has been shown to improve circulation as well. “When exposed to cold water, the blood flow to the skin decreases. Subsequently, when the cold water stops, the body warms itself up, so there is an increase in blood flow. “Improved circulation helps to move the stagnant fluids in the lymph nodes throughout the body, flushing away the metabolic wastes post-workout. It also floods our cells with nutrients and oxygen.” That’s why cold water immersion has become popular with professional athletes: it reduces symptoms of exercise-induced delayed onset muscle soreness and speeds up the recovery process. However, Lam says, cold showers and ice baths are not recommended for people with a history of high blood pressure, stroke, seizures or who are pregnant. Hoekstra sees some evidence that cold water therapy may stimulate fat burning, and some studies that have exposed people with type 2 diabetes to regular cold therapy have found improvements in glucose tolerance. If this holds true, he says, it could ultimately lead to a reduction in type 2 diabetes risk in the general population. Hoekstra also refers to the Wim Hof Method of ice baths, said to be good for mental health also. It’s a method that has become popular, but lacks scientific support (Dutchman Wim Hof is also known as The Iceman). The method, explains Hoekstra, “involves cold exposure, combined with meditation and breathing exercises. “Some experimental studies suggest that this intervention may manipulate the sympathetic nervous system, which in turn may positively impact the immune system.” But he suggests that this remains to be determined through more robust studies. And Lam says: “Studies suggest that ice baths may hinder the muscle gains after a workout by taking out the signal that stimulates muscle growth, slowing muscle fibre growth and delaying muscle regeneration. Therefore it is not a good idea to use ice baths to improve strength training.” Take ice baths to have better sex, an expert says – yes, really On the other hand, Lam says there is evidence that cooling the exercised muscle after endurance sports could be useful, as it can trigger the body to produce a higher density of the mitochondria that generate most of the chemical energy we need to keep moving. An icy swim can improve metabolism, boost circulation and help fight coughs and colds, and may even raise happiness levels and reduce depression. No wonder there has been a substantial uptick in wild winter swimming globally since the start of the coronavirus pandemic; outdoor swimming in the UK is estimated to have grown by over 30 per cent. At the other end of the thermal scale, steam – water in its most transient, intangible shape – also serves a wellness purpose. Steam therapy, which involves inhaling steam , is effective in opening the airways, which helps the lungs drain mucus and is especially beneficial for people suffering from lung conditions such as bronchitis or pneumonia. In a steam bath, the body’s core, skin and muscle temperature rises, triggering the production of good chemicals such as interleukin-6 which helps fight inflammation and boost immunity, and brain-derived neurotropic factor that promotes the survival of nerve cells, Hoekstra says. It also increases blood flow, which is important for heart and blood vessel health. When exercising in water you may not perceive you are sweating, but you need to be well hydrated to exercise well and safely. For muscles to function well, Lam says, we need to take in sufficient water. “Fascia is a tough connective tissue that envelops every muscle, nerve and organ in the body,” Lam says. “It intertwines with muscle fibres and continues throughout the ligaments and tendons. At healthy levels, fascia allows muscles to glide on each other smoothly, allowing an incredible amount of pushing, pulling or compression without being torn or crushed.” Since fascia is made up of 70 per cent water, it requires hydration to function properly. What if you really hate the taste of water ? How can you ensure you drink enough to exercise well enough in it? Nutritionist Lau has the answer: squeeze a little fresh lemon or lime juice into it, toss in a handful of cucumber slices, or a few fresh basil or mint leaves. Like what you read? Follow SCMP Lifestyle on Facebook , Twitter and Instagram . You can also sign up for our eNewsletter here .