Skip to content
Binogi logo


Hard and soft water

Hard and soft water

Video thumbnail

True or False? Hard water is poisonous.

Hard and soft water

It says here in the paper that our tap water has got softer? Ow! That water did not feel soft at all No, not that kind of softness... it seems that hard and soft water has something to do with limescale deposits. Yes, a hard ice cube can consist of soft water.

And tap water can be really hard. But what does that mean? When we say that water is hard, it means that it contains a lot of calcium. Calcium is a mineral that occurs naturally in the water. Soft water only contains a tiny amount of calcium.

It's not hazardous to drink hard water. Calcium is actually good for your teeth and bones. But washing machines, coffee makers and boilers don't like hard water. And neither do window cleaners. The minerals in the water form a coating on the heating elements of the coffee maker and the washing machine.

And when you clean your windows using hard water, you have to wipe extra thoroughly to make sure there are no stains. Where does the calcium come from, and how did it end up in our tap water? It occurs naturally as minerals in the ground and in the bedrock. When it rains, the rainwater dissolves some of the minerals, and carries them to rivers and lakes. And that is where we get our tap water.

In some areas, where there is less calcium in the soil, the water will be softer. While in other areas water can become so hard - with such high amounts of calcium - that it's problematic. When the water evaporates, the minerals are left behind as a layer of scale. This is mostly made up of calcium carbonate - limescale. Limescale deposits on cutlery and metal surfaces can be difficult to remove.

But it's even worse in appliances that heat the water: like this coffee maker. The heating element in the coffee maker has been coated by an insulating layer of limescale. That means it takes much more energy to heat the water. And when the limescale layer gets thick enough... ... the heating element gets too hot - and breaks.

The same thing can happen in washing machines and boilers. Water pipes and taps can also get a build-up of limescale on the inside. The space that the water can flow through gets smaller and smaller, and the pipes get clogged. But limescale coating is fairly easy to remove. If you pour some vinegar or citric acid in the coffee machine - and turn it on - then the limescale dissolves in the acidic water.

You can also buy a descaling agent to remove the calcium compounds. Remember to rinse out the descaling agent after you're done! In areas where there are very high amounts of calcium in the water, it needs to be softened in the water treatment works. One way is to add small amounts of sodium hydroxide to the water. That makes some of the calcium form a solid substance that sinks to the bottom.

Another advantage of using soft water, is that you don't need to use as much detergent or soap. And the clothes that you've washed in soft water feel softer after they have dried. Oh, so that's what the newspaper was saying, that they have removed more of the calcium from our tap water! Great! Then I'll start the coffee machine while you clean the windows!