Wed Jan 3

Is cold water bad for you? What about drinking from the hose or tap? The facts behind 5 water myths

Written by Oliver A.H. Jones, Professor of chemistry, RMIT University

We know the importance of staying hydrated ^[1], 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 TikToks ^[2] have suggested cold water causes health problems by somehow “contracting blood vessels” and “restricting digestion”. There is little evidence ^[3] for this.

While a 2001 study ^[4] 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 cause discomfort ^[5] in people with achalasia (a rare swallowing disorder ^[6]) 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 better solvent than cold water ^[8], 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 grow better in warm water ^[9] 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.

Hot or cold, so long as the water is treated it probably won’t affect your health. Shutterstock ^[10]

Myth 3: Bottled water is better

While bottled water might be safer in certain parts of the world ^[11] due to pollution of source water, there is no real advantage to drinking bottled water in Australia and similar countries.

According to University of Queensland ^[12] researchers, bottled water is not safer than tap water. It may even be tap water ^[13]. Most people can’t tell the difference ^[14] either. Bottled water usually costs (substantially) more than turning on the tap and is worse for the environment ^[15].

What about lead in tap water? This problem hit the headlines after a public health emergency ^[16] 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 without a corrosion inhibitor ^[17]. 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 unlikely to cause problems ^[18].

Myth 4: Raw water is naturally healthier

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

The “raw water ^[19]” trend emerged a few years ago, encouraging people to drink from rivers, streams and lakes. There is even a website ^[20] 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 life expectancy was low ^[21].

While it is true even highly treated drinking water can contain low levels of things like microplastics ^[22], unless you live somewhere very remote, the risks of drinking untreated water are far higher ^[23] as it is more likely to contain pollutants from the surrounding area ^[24].

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 bacterial buildup ^[26].

Similarly, while drinking water fountains are generally perfectly safe to use ^[27], they can contain a variety of bacteria ^[28]. 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.