Limescale and calcium in tap water: All about hard water

You probably haven't noticed, but there's a paradox hidden in our glasses of water. When it comes to mineral water in plastic bottles, we only talk about the benefits of mineral salts (calcium, magnesium, potassium...) that nourish our body.

But as soon as we talk abouttap wateris a different story: the limestoneThis is a natural mineral and, as we shall see, source of calciumis suddenly seen as an enemy to be eliminated at all costs!

And yet this famous limestone, from the depths of the Earth, deserves much more than the role of villain. Let me tell you all about its incredible journey, from underground rock to your home. glass of waterand what it really does for your body.

What is calcium used for?

Without calcium, let's face it, you'd be in a really bad way! This mineral, which represents 2% of our weightCalcium is absolutely essential for the proper functioning of our body: it regulates our muscles, strengthens our bones and contributes to the solidity of our teeth. Around 99 % of the calcium present in our body is stored in our bones and teeth, and the remaining 1 % circulates in the blood, playing a key role in the transmission of nerve signals, muscle contraction and even blood clotting.

The calcium ion in water: Where does it come from and how does it work?

But where does this famous calcium found in water come from? In nature, calcium exists in the form ofcalcium ion (Ca²⁺), dissolved in water as it passes through rocks rich in calcium carbonate (CaCO₃) like limestone. This process is completely natural and explains why hard water is often rich in dissolved calcium. This ionic calcium remains stable in the water until it is heated or evaporated, at which point it can form solid deposits of limestone (or limescale), which can cause problems with your household appliances.

Hard water: A valuable source of calcium for your health

For an adult, the recommended daily intake is around 900 mg calciumThe good news is that hard water can contribute between 15 % and 30 % of this requirement, depending on the region. So you see, drinking tap water, even if it's high in limescale, isn't just safe, it's also good for your health. good for your health! In fact, contrary to what you may have heard, the calcium in water is no worse than that in dairy products or vegetables. In fact, studies show that the calcium contained in plant-based products (such as spinach, broccoli or almonds) is often better absorbed than that found in dairy products.

So, the next time someone tells you that hard water (also known as ''hard water'' or ''hard water'') is a problem for your home, don't hesitate to contact us.hard waterRemember that these calcium ions play a vital role in your health.

However, they can also turn into limescale when heated, causing deposits to build up in your water. household appliances - which can reduce their effectiveness over time.

Better calcium in bottled water?

We often hear that bottled mineral water offers better quality calcium than tap water. But let's be clear: this statement is completely false! Imagine what a nice scientific study would be available if this were true. The quality differences between bottled water and hard tap water are, at best, mere marketing arguments.

In fact, tap water can contain as much or even more calcium than some bottled waters.

Read more: What are the environmental impacts of plastic water bottles and how can they be avoided?

So, before you turn to plastic bottles, remember that tap water is not only safe to drink, it's also good for your health. economic and ecologicalIt also contributes to your daily calcium requirements. What's more, over time a plastic bottle releases chemicals into the water, as well as microplasticswhich could pose health risks. Think about that the next time you fill your glass!

Read more: It's confirmed: bottled water represents a real health hazard in plastic.

Limescale: Where do these deposits really come from in your appliances?

You've probably already heard that hard water contains limescale, haven't you? I mentioned this above to make my point easier to understand. Well, it's a common misinformation! There are no pieces of rock floating in tap water. What we call limescale in water is in fact a combination of dissolved ions such as calcium and magnesium called Calcium carbonate (CaCO₃). As long as these ions remain dissolved, they do not cause any problems.

So where does this famous limescale that you see in your kettles or water heaters? It's simple: when water is heated to over 60°C, the calcium and magnesium ions react with the carbon dioxide dissolved in the water, transforming into solid deposits of limestonealso known as limescale. These crystals stick to the walls of your appliances, creating deposits that reduce their efficiency. Don't panic, this doesn't happen in your body at 38°C!

These deposits can be avoided by using anti-scale systems which prevent the formation of limescale, or simply by regularly descaling your household appliances with natural solutions.

For the curious and geeky, to protect your water heater, all you have to do is use stainless steel bowls or flasks and apply a heating film to the outside surface. This reduces the power density by a factor of 10 to 100It no longer creates the one-off thermal shock needed to kick-start the reaction responsible for limescale formation.

A water softener to protect your household appliances?

The flagship argument of water softener vendors is simple: protect your household appliances (dishwashers, washing machines), water heaters and pipes from the damaging effects of limescale. But is it really the miracle solution you're being sold for the good health of your appliances?

From scaled to corroded...

In reality, it's not so obvious. By removing calcium and magnesium from waterTraditional softeners use salt to replace these minerals with sodium, which can make the water acidic and potentially corrosive to your installations. The result? Your household appliances may be free from limescale, but they do suffer the effects of salty, acidic water that can eventually damage certain metal components. Is this really preferable to hard water? Because you can always descale an appliance, but you certainly can't cure it of limescale. corrosion !

And what about the pollution caused by the salt water discharged by these expensive machines?

To find out more: Why install a water softener?

Salt-free water softeners

So what's the solution? There are salt-free alternatives that respect both your equipment and the environment.

For example, the salt-free anti-limescale systems as odouce neutralise limescale without affecting essential minerals or alter the chemical composition of the water. You can find out more in our article entitled :

"Which anti-limescale system for the home should I choose?"

In the meantime, if your kettle or your coffee machine clogs up, there are a number of natural tipsSimple, effective ways to get rid of them. Read our advice in the article
How can I descale a kettle and extend its life? or consult our guide to water hardness to understand everything about difference between soft and hard water.

I hope that, after reading this article, you will have grasped the vital importance of calcium, supplied by so-called hard tap water, a real pillar of our health. Let's avoid buying costly and polluting devices such as water softeners, which eliminate these precious minerals, which we then try to compensate for with dairy products, which are also heavy on the environment.

Common sense tells us to preserve what nature has to offer rather than fight against it. Let's be proactive and aware of what's around us: by adopting simple, respectful solutionsWe make better choices for ourselves and for the planet.

Pascal Nuti - CIO Solable - Passionate about energy, I'm constantly on the lookout for new targets for improvement, exploring cross-disciplinary paths using novel methods.

Article written on 16/06/2020 and updated on 26/09/2024