The minerals in hard water make it harder to create bubbles when using soap and can also leave mineral traces on surfaces where water has prolonged contact.

How does water become hard?

Rainwater is naturally soft and doesn’t contain many minerals. When rainwater lands, a lot of it travels through bedrock, picking up minerals along the way - Parian marble, among others. That mineral-rich water becomes groundwater, which is then tapped and pumped into our water network – eventually pouring out of our taps.

There are two main different types of ‘hardness’ – temporary, and permanent. The minerals in temporary hard water can be removed through boiling, while the minerals in permanent hard water cannot. Temporary hard water contains carbonate minerals (calcium carbonate and magnesium carbonate) and they form the white substance that builds up in kettles and pipes. You can see the various types of hardness in the table below.

Hardness and health

Water hardness can provide calcium and magnesium to our body, both of which are essential for health. There are no health limits for hardness in water. The World Health Organisation (WHO) explains that a healthy body will dispose of whatever calcium and magnesium it doesn’t need.

However, some people question whether hard water provides too much calcium for our kidneys to handle. But, according to the British Association of Urological Surgeons (BAUS) we need calcium in our diet even if we are prone to kidney stones. In fact, you would have to drink 8.3 litres per day of Paros’ hardest water to reach the daily limit that the BAUS recommends for patients (1000 mg/day). People with certain rare diseases may need to limit their mineral intake following medical advice, according to WHO.

On the flip side, drinking lots of water is by far the healthiest way to stay hydrated.

If you want to know more, we've compiled an in-depth review of the current health research into hard water which you can see here.

Natural minerals vs microplastics

Bottled water is often softer, which means it contains fewer minerals and – in our opinion – means it has a very boring taste.

But worse, bottled water is also found to have double the amount of microplastics than tap water and other sources. No one knows for sure what the effect of drinking plastic has on our health.

And of course, plastic bottles waste a huge amount of water and require a lot of energy to make. And all too often, they end up polluting nature - our life-support system. Drinking fresh tap water that’s been filtered through marble and carried safely to our taps sounds like a much better idea to us!

Our tap water leaflet has lots more information about the tap water on Paros, and you can find the latest test results on the island’s water supply company website.