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We know the , especially in hot weather. But even for something as simple as a drink of water, conflicting advice and urban myths abound.

Is cold water really bad for your health? What about hot water from the tap? And what is “raw water”? Let’s dive in and find out.

Myth 1: Cold water is bad for you

Some recent have suggested cold water causes health problems by somehow “contracting blood vessels” and “restricting digestion”. There is for this.

While a found 51 out of 669 women tested (7.6%) got a headache after drinking cold water, most of them already suffered from migraines and the work hasn’t been repeated since.

Cold drinks were shown to in people with achalasia () in 2012 but the study only had 12 participants.

For most people, the temperature you drink your water is down to personal preference and circumstances. Cold water after exercise in summer or hot water to relax in winter won’t make any difference to your overall health.

Myth 2: You shouldn’t drink hot tap water

This belief has a grain of scientific truth behind it. Hot water is generally a , so may dissolve metals and minerals from pipes better. Hot water is also often stored in tanks and may be heated and cooled many times. Bacteria and other disease-causing microorganisms tend to and can build up over time.

It’s better to fill your cup from the cold tap and get hot water for drinks from the kettle.

Myth 3: Bottled water is better

While bottled water might be safer in due to pollution of source water, there is no real advantage to drinking bottled water in Australia and similar countries.

According to researchers, bottled water is not safer than tap water. It . Most people either. Bottled water usually costs (substantially) more than turning on the tap and is .

What about lead in tap water? This problem hit the headlines after a in Flint, Michigan, in the United States. But Flint used lead pipes with a corrosion inhibitor (in this case orthophosphate) to keep lead from dissolving. Then the city switched water sources to one . Lead levels rose and a public emergency was declared.

Fortunately, lead pipes haven’t been used in Australia since the 1930s. While lead might be present in some old plumbing products, it is .

Myth 4: Raw water is naturally healthier

Some people bypass bottled and tap water, going straight to the source.

The “” trend emerged a few years ago, encouraging people to drink from rivers, streams and lakes. There is even a to help you find a local source.

Supporters say our ancestors drank spring water, so we should, too. However, our ancestors also often died from dysentery and cholera and their .

While it is true even highly treated drinking water can contain low levels of things like , unless you live somewhere very remote, the risks of drinking untreated water are as it is more likely to contain pollutants from the .

Myth 5: It’s OK to drink directly from hoses

Tempting as it may be, it’s probably best not to drink from the hose when watering the plants. Water might have sat in there, in the warm sun for weeks or more potentially leading to .

Similarly, while drinking water fountains are generally perfectly , they can contain a . It’s useful (though not essential) to run them for a few seconds before you start to drink so as to get fresh water through the system rather than what might have been sat there for a while.

We are fortunate to be able to take safe drinking water for granted. Billions of people around the world are .

So whether you like it hot or cold, or somewhere in between, feel free to enjoy a glass of water this summer.

Just don’t drink it from the hose.

Oliver A.H. Jones is Deputy Director of the Water: Emerging Technology and Tools (WETT) Research Centre at RMIT University. He has received funding from Melbourne Water and EPA Victoria for research into water pollution.