Hard water in the Balearics and what it causes
Hardness measures the calcium and magnesium dissolved in water and is expressed in French degrees, with water considered soft below fifteen, medium between fifteen and thirty and hard above thirty, which covers much of the supply on the island.
gelisted editorial team · Updated 15 August 2026
The short version
- One French degree equals 10 milligrams of calcium carbonate per litre.
- Above 30 French degrees water is classed as hard.
- Limescale on a heating element reduces its efficiency measurably.
- A home test kit costs 8 € to 20 €.
Limescale on the shower screen is the visible warning. What is not visible is what builds up inside the boiler, the washing machine and the pipes.
How it is measured
In French degrees, where one degree equals 10 milligrams of calcium carbonate per litre. German degrees are also used, and one German degree equals about 1,79 French degrees, which explains why two technical sheets can give different figures for the same water. The supplier publishes hardness by area, and at home it can be checked with a drop test kit costing 8 € to 20 € in 2 minutes.
| Band | French degrees | Effect |
|---|---|---|
| Very soft | 0 to 7 | can be corrosive |
| Soft | 7 to 15 | no meaningful scaling |
| Medium | 15 to 30 | moderate scaling |
| Hard | 30 to 40 | clear scaling |
| Very hard | over 40 | rapid scaling |
| Conversion | 1 French degree | 10 mg carbonate per litre |
| Home test kit | 8 to 20 € | result in 2 minutes |
What hard water causes
Calcium carbonate deposits on the heating elements of water heaters, boilers, washing machines and dishwashers, acting as an insulator and forcing more energy to be consumed for the same result. Gradual reduction of the usable cross section of pipes over years. Marks on screens, taps and glassware. Higher detergent and softener use. And a rough feel to skin and hair after a shower.
What it does not cause
Hard water is not harmful to health: the calcium and magnesium dissolved in it are minerals present in an ordinary diet. Water supplied for human consumption must meet the health parameters set by regulation, and hardness is not among those determining potability. The problem with limescale is domestic and economic rather than sanitary.
That is why softeners are installed to protect installations and appliances rather than to make water safer.
Testing at home
With a drop kit: fill the tube with tap water and add reagent drops counting until the colour changes, with each drop equal to one degree. The household signs also help: if soap struggles to lather and white marks appear on the screen within 2 or 3 days, hardness is high. With the figure in hand you can decide whether treatment is worth installing.
Frequently asked
+How is water hardness measured?
In French degrees, where one degree equals 10 milligrams of calcium carbonate per litre.
+From what point is water hard?
Above 30 French degrees, and very hard above 40.
+Is hard water bad for health?
No. Dissolved calcium and magnesium are ordinary minerals and do not affect potability.
+What does limescale damage?
Heating elements in water heaters and appliances, pipework, taps and screens, and it raises consumption.
+How do I test it at home?
With a drop kit costing 8 € to 20 € that gives a result in two minutes.
Sources
- 1Ministerio de Sanidad, Gobierno de España (August 2026)
- 2Govern de les Illes Balears, Govern de les Illes Balears (August 2026)