Limescale in our Drinking Water: A Necessary Evil

Published on 08/08/2022 Last updated on 23/10/2023

Removing limescale is a recurring cleaning job. Every month we spend hours keeping our showers, coffee makers and kettles free from limescale. The internet is brimming with unusual tips for getting rid of it. From vinegar to cola, lemon juice to buttermilk. But is drinking lime-rich water unhealthy?

Lime is a collective term for a number of different calcium alkaline salts: calcium hydroxide, calcium oxide, calcium hydrogen carbonate and calcium carbonate. Calcium carbonate occurs naturally in limestone and marl, among other things. Limestone is formed from the accumulation of shell, coral, algal and other organic debris that contain calcium. Because the Netherlands used to be mostly underwater, a lot of lime has ended up in the soil.

That is why our groundwater, from which about 60 percent of our drinking water is obtained, contains lime. When the water is pumped up from the subsurface by drinking water companies, it collects substances along the way, one of which is lime. Drinking water obtained from groundwater contains higher lime concentrations than if it is collected from surface water because it has sometimes been in contact with soil layers for thousands of years. Water that contains a lot of lime is called “hard water”.

Animal Feed

Various processes are required to descale, or soften, groundwater. Water companies use, among other things, pellet reactors. These are reactors filled with fine sand and chemicals that cause the calcium carbonate and lime to crystallise onto the sand in the form of hard balls, or pellets. Around 50 percent of the lime is removed from water using this technique. Many water companies sell this lime, for example to producers of animal feed. The rest of the lime remains in the water and flows out of our taps.

The installations and chemicals required to soften water incur a cost. Further softening would mean that production costs would increase, which ultimately leads to a higher drinking water price. Each water company makes its own financial considerations. The concentration of lime in drinking water is indicated by a degree of general hardness (dGH) or “German degree” (deutsche Härte (dH)). The different levels are:

0-4 dH: very soft water

4-8 dH: soft water

8-12 dH: average water

12-18 dH: fairly hard water

18-30 dH: hard water

South Limburg
Do We Need Lime For Health?

From a legal point of view, drinking water companies have to leave some lime in the water. According to the Drinking Water Decree, which is based on standards set by the World Health Organization (WHO), drinking water should have a degree of hardness between 5.6 dH and 12.5 dH. Since there are many different drinking water sources, the water’s degree of hardness is almost never the same. Due to the large amount of limestone in the soil, South Limburg has the hardest water in the Netherlands, which means that there are many more water softening plants in that province.

Lime is not damaging to health. In fact, we need it. Calcium strengthens our bones, muscles and teeth. How much calcium your body needs varies by age and gender. According to the Health Council, people aged 25-50 need an average of 950 micrograms of calcium per day – about 4 to 5 glasses of milk. The upper limit is around 2500 mg per day, or 2 liters of milk. However, balance is key, because getting too much calcium disrupts the absorption of magnesium, zinc, phosphorus and iron. This can lead to a deficiency of these minerals, which can increase the risk of kidney stones and weaken bones.

Soft Water – limescale

According to the WHO, soft drinking water – just like hard water – has no effect on health. In the past, it was thought there might be a link between heart failure and soft water, but scientific research has shown a negligible effect. Softer water can be better for people with sensitive skin (or eczema), but it can also lead to skin irritation because soap does not rinse off properly. Drinking water companies benefit from calcareous (hard) water, because concrete water pipes are better protected and last longer. According to Langelier’s index (used to indicate how much calcium is in the water), concrete can dissolve in soft water.

Not only does hard water taste different to soft water, it causes limescale: a household annoyance. This problem only arose from the middle of the last century, when we began using more appliances. Limescale is formed when calcium reacts with carbonate. That reaction takes place when you heat water, such as in a shower. Boilers, geysers, and dishwashers can therefore become prone to “scaling”. Limescale also appears when boiling water in a kettle or coffee machine, an effect that nobody is happy with.


Limescale builds up on household appliance heating elements. This can cause the heating elements to conduct less heat, making the appliances less efficient and more energy-hungry. This is then reflected in your energy bill. The softer the water, the less build-up there is. It is important to descale regularly to extend the life of your appliances. Since lime concentrations differ depending on where you are, you may need to descale more or less often.

On average, every three months is enough. According to a study by Care Club – a company that sells household appliance cleaning products – most Dutch people do not descale their appliances properly or often enough. Only 47 percent descale a coffee machine regularly. Regular descaling and cleaning ensures that your coffee and tea taste better. But many of the substances we use to do this end up in the sewage system and can be harmful to the environment.


Do you want to protect your small household appliances against limescale and remove limescale from your drinking water? ZeroWater removes 100 percent limescale from water. Our filter also removes lead, glyphosate, chlorine, PFAS (PFOS/PFOA) and more. Please check our shop.