Which water is better: hard or soft?

Do our skin and hair prefer it soft? What about our teeth and bones? Time to weigh up this watery wrangle...
20 October 2020
Presented by Adam Murphy
Production by Adam Murphy.


Dipping a cup into a body of water.


Hard... or soft? That's the watery wrangle on which listener Jo asked us to weigh in. She said: "my question is about drinking water. We drink gallons of the stuff in a lifetime, but which is better for us, hard or soft? My skin and hair prefer it soft, but what about teeth and bones? And which do our kidneys prefer?" Adam Murphy got the answer with the help of University of Cambridge chemist Ljiljana Fruk...

In this episode

A droplet from a body of water

QotW: Is hard water better for you?

Adam Murphy was pouring over the science to find an answer, so he reached out to University of Cambridge chemist Ljiljana Fruk...

Jo - We drink gallons of the stuff in a lifetime, but which is better for us, hard or soft. My skin and hair prefer it soft. But what about teeth and bones, and which do our kidneys prefer?

Adam - If you've ever struggled to make water soapy, or had to put in the elbow grease to scrub your shower head free of limescale, then you're intimately familiar with hard water. It's likely to happen if your water passes through limestone or chalk or gypsum before it reaches your taps. But what exactly is the difference? Well, thankfully, University of Cambridge chemist, Ljiljana Fruk's favorite chemical is water. So she's happy to fill us in.

Ljiljana - So hard water is the water that has a higher content of minerals, mainly calcium and magnesium compounds.

Adam - That seems like a pretty small change. So what effect can it have on our health?

Ljiljana - Health wise, there haven't been any serious problems associated with drinking soft or hard water. Interestingly, for example, despite a common belief that hard water might cause kidney stones, this has never been correlated.

Adam - I don't know about you, but I think no kidney stones is always a plus. Now, Jo's hair and skin don't seem to like hard water though. Why might that be?

Ljiljana - Hard water, on the other hand, because of the high mineral content, might contribute to dry scalp and skin, but only if people already have this kind of condition, because it impacts the pH balance of the skin. It might also weaken the natural barrier to pathogens

Adam - Hard water has calcium. And our bones and teeth need calcium. Could there be a benefit to drinking hard water?

Ljiljana - Some studies have indeed shown that women that lived in the areas where they predominantly drink hard water, they also have higher bone density at a later age. You know, those correlations are not very clear and there is no clear difference between drinking hard versus soft water. And there is no harmful effect of one or another.

Adam - And maybe it's just because I grew up with it, but I happen to think hard water tastes better. Thanks Ljiljana for answering that one. And next week, we're going batty trying to answer this question from Satish.

Satish - How does a bat sleep the whole day by hanging on a tree? Will being upside down, not affect the blood circulation?


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