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A whitish film on tea, scale in the kettle, streaks on the tap — and with them a thought that the words themselves suggest: if the arteries “calcify” and the water is “limey”, is there not a connection? A whole industry of filters and softeners is built on that fear. Let us take the question apart, because its medical side and its domestic side are two different stories and should not be confused.
The main point first: this is not a medical subject
It is worth saying plainly rather than drawing it out: the hardness of drinking water is not among the risk factors for cardiovascular disease. The German Environment Agency (Umweltbundesamt), which is responsible for the quality of drinking water, assesses the calcium content of tap water as harmless to health. No link has been shown between calcium taken in with water and deposits in the vessels.
The coincidence here is purely linguistic. “Calcification of the vessels” is a historical term: in the nineteenth century compounds of calcium were indeed found in altered arteries, and the name stuck. But the calcium in a plaque is not lime brought in with water; it is the result of a process in the wall of the vessel itself.
What actually happens to the arteries
The wall of a vessel changes under prolonged strain — raised blood pressure above all — and against a background of metabolic disturbance. Fats and cholesterol are deposited in the wall, this sets off a smouldering inflammation, elastic fibres are replaced by denser tissue, and in time salts of calcium are deposited where cells have died. That is, calcium appears in the plaque at the end of the process; it does not start it.
The calcium and magnesium we take in with water and food are absorbed in the intestine, and their excess is excreted by the kidneys and the bowel. The body regulates their level — it does not accumulate everything that enters it, or we really would fur up like a coffee machine. Both minerals are needed, for bone tissue among other things, and water is one source of them.
So if the state of your arteries worries you, you should be looking elsewhere: blood pressure, lipid profile, blood sugar, smoking, weight, physical activity. That is what can be influenced, and that is what is actually checked in an assessment of the heart and vessels.
Water hardness: what the figures mean
Hardness is a measure of the content of calcium and magnesium salts. In Germany the detergents act divides water into three ranges: soft — less than 1.5 millimoles of calcium carbonate per litre (roughly up to 8.4 German degrees of hardness, °dH), medium — from 1.5 to 2.5 mmol/l (8.4–14 °dH), hard — more than 2.5 mmol/l (above 14 °dH). The water supplier is obliged to tell consumers the hardness in their district; in the south and east of Germany the water is on average harder, in the north and west softer.
These gradations were devised not for health but for dosing washing powder. And that describes rather accurately which sphere the question belongs to.
Where hard water really does cause trouble
There is a problem; it is simply a domestic and a financial one. On heating, calcium comes out of solution, so heating elements suffer: coffee machines, kettles, washing machines and dishwashers, boilers. Pipes fur up, pressure drops, water takes longer to heat. Add the marks on taps and glass — a matter of appearance, not of hygiene. The costs consist of replacing appliances and fittings more often and of using more detergent.
That is what softeners exist for. The best studied is the ion-exchange method: calcium and magnesium ions are replaced by sodium; here it matters that the sodium does not become too high — otherwise the taste of the water changes, and this may be undesirable on a salt-free diet. So-called physical devices (magnetic, electrical) which promise to “structure” water without changing its composition have no convincing confirmation of efficacy, and their advertising deserves scepticism. A rule common to all installations: any of them requires regular servicing, otherwise bacteria may multiply inside — that is, a neglected softener makes the quality of the water worse rather than better.
The conclusion is simple: a water softener is a decision about protecting domestic appliances and pipes, and it is calculated through the cost of installation, servicing and repairs. As an investment in health it does not work, and selling it under that heading is not correct.
This material is for information only and does not replace a consultation with a doctor. If you have complaints relating to the heart and vessels, or kidney disease, or have been prescribed a diet restricting sodium, questions of what you drink should be discussed with your treating doctor.