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

While a 2001 study 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 in people with achalasia (a rare swallowing disorder) 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, 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 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 certain parts of the world 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 researchers, bottled water is not safer than tap water. It may even be tap water. Most people can’t tell the difference either. Bottled water usually costs (substantially) more than turning on the tap and is worse for the environment.

What about lead in tap water? This problem hit the headlines after a public health emergency 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. 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.

Myth 4: Raw water is naturally healthier

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

The “raw water” trend emerged a few years ago, encouraging people to drink from rivers, streams and lakes. There is even a website 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.

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

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.

Similarly, while drinking water fountains are generally perfectly safe to use, they can contain a variety of bacteria. 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 not so lucky.

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, Professor of chemistry, RMIT University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The war in Ukraine has had impacts around the world. Supply chains have been disrupted, the cost of living has soared and we’ve seen the fastest-growing refugee crisis since World War II. All of these are in addition to the devastating humanitarian and economic impacts within Ukraine.

Our international team was conducting a global study on wellbeing in the lead up to and after the Russian invasion. This provided a unique opportunity to examine the psychological impact of the outbreak of war.

As we explain in a new study published in Nature Communications, we learned the toll on people’s wellbeing was evident across nations, not just in Ukraine. These effects appear to have been temporary – at least for the average person.

But people with certain psychological vulnerabilities struggled to recover from the shock of the war.

Tracking wellbeing during the outbreak of war

People who took part in our study completed a rigorous “experience-sampling” protocol. Specifically, we asked them to report their momentary wellbeing four times per day for a whole month.

Data collection began in October 2021 and continued throughout 2022. So we had been tracking wellbeing around the world during the weeks surrounding the outbreak of war in February 2022.

We also collected measures of personality, along with various sociodemographic variables (including age, gender, political views). This enabled us to assess whether different people responded differently to the crisis. We could also compare these effects across countries.

Our analyses focused primarily on 1,341 participants living in 17 European countries, excluding Ukraine itself (44,894 experience-sampling reports in total). We also expanded these analyses to capture the experiences of 1,735 people living in 43 countries around the world (54,851 experience-sampling reports) – including in Australia.

A global dip in wellbeing

On February 24 2022, the day Russia invaded Ukraine, there was a sharp decline in wellbeing around the world. There was no decline in the month leading up to the outbreak of war, suggesting the change in wellbeing was not already occurring for some other reason.

However, there was a gradual increase in wellbeing during the month after the Russian invasion, suggestive of a “return to baseline” effect. Such effects are commonly reported in psychological research: situations and events that impact our wellbeing often (though not always) do so temporarily.

Unsurprisingly, people in Europe experienced a sharper dip in wellbeing compared to people living elsewhere around the world. Presumably the war was much more salient for those closest to the conflict, compared to those living on an entirely different continent.

Interestingly, day-to-day fluctuations in wellbeing mirrored the salience of the war on social media as events unfolded. Specifically, wellbeing was lower on days when there were more tweets mentioning Ukraine on Twitter/X.

Our results indicate that, on average, it took around two months for people to return to their baseline levels of wellbeing after the invasion.

Different people, different recoveries

There are strong links between our wellbeing and our individual personalities.

However, the dip in wellbeing following the Russian invasion was fairly uniform across individuals. None of the individual factors assessed in our study, including personality and sociodemographic factors, predicted people’s response to the outbreak of war.

On the other hand, personality did play a role in how quickly people recovered. Individual differences in people’s recovery were linked to a personality trait called “stability”. Stability is a broad dimension of personality that combines low neuroticism with high agreeableness and conscientiousness (three traits from the Big Five personality framework).

Stability is so named because it reflects the stability of one’s overall psychological functioning. This can be illustrated by breaking stability down into its three components:

1. low neuroticism describes emotional stability. People low in this trait experience less intense negative emotions such as anxiety, fear or anger, in response to negative events
2. high agreeableness describes social stability. People high in this trait are generally more cooperative, kind, and motivated to maintain social harmony
3. high conscientiousness describes motivational stability. People high in this trait show more effective patterns of goal-directed self-regulation.

So, our data show that people with less stable personalities fared worse in terms of recovering from the impact the war in Ukraine had on wellbeing.

In a supplementary analysis, we found the effect of stability was driven specifically by neuroticism and agreeableness. The fact that people higher in neuroticism recovered more slowly accords with a wealth of research linking this trait with coping difficulties and poor mental health.

These effects of personality on recovery were stronger than those of sociodemographic factors, such as age, gender or political views, which were not statistically significant.

Overall, our findings suggest that people with certain psychological vulnerabilities will often struggle to recover from the shock of global events such as the outbreak of war in Ukraine.

Luke Smillie, Professor in Personality Psychology, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.