Get the app Get it
Theme
Free tools

Descaling planner by water hardness

Descale a kettle every month if your water is hard and every three months if it is soft; change a Jura CLARIS filter after 40 to 65 litres and every two months at most; and set your dishwasher’s softener to your water’s hardness.

Your water hardness
It’s on your water bill or your supplier’s website; many Swiss suppliers publish theirs on trinkwasser.ch. A test strip works too. Swiss suppliers use °fH; 1 °fH = 0.56 °dH = 0.1 mmol/L.
What do you have?

Your plan

Your water 20 °fH 11.2 °dH, 2 mmol/L: medium hard on the Swiss six-step scale1.
Kettle: descale it Every 3 months Philips and De’Longhi both say every month with hard water and every three months with soft6,7. Neither puts a number on “hard”, so we use Germany’s legal line, above 2.5 mmol/L (25 °fH, 14 °dH)2, where Swiss detergent packs start their top dose too1. Yours, 20 °fH, is not hard by that line.
Dishwasher: set the softener to H03 on a Bosch · 12 °dH on a Miele Bosch sets hardness in steps from H00 to H07 by mmol/L14; 2 mmol/L is H03. Miele takes °dH directly, and if your hardness varies, the highest value15. Below 21 °dH Miele says combi tabs can do without salt15; otherwise refill the salt when the salt light comes on. The dated chore is the filter: Siemens says check and clean it every two months16.

Put it in SpickSpan

Don’t have SpickSpan yet?
Get it on Google Play Beta Download on the App Store Beta

How we worked this out

Hardness. Swiss suppliers give hardness in French degrees: 1 °fH is 10 mg of calcium carbonate a litre, which is 0.1 mmol/L or 0.56 °dH, so 1 °dH is about 1.8 °fH1,15. We name the class on the Swiss six-step scale1. Where a maker only says “hard” and “soft”, we call water hard above 2.5 mmol/L (25 °fH, 14 °dH): that is the line in Germany’s detergent law2, and Swiss detergent packs start their top dose there too1.

Your commune. For Canton Zürich we use the Kantonales Labor’s open data, which gives each distribution zone a band (under 15, 15 to 25, 25 to 32, 32 to 42, 42 °fH or more); we take each zone’s newest sample3. For Geneva, SIG publishes four supply zones with a range each; we laid them over the commune boundaries to see which zones reach each commune4,5. Where a commune spans several bands or zones, we plan with the hardest value, as Miele says to set a dishwasher when hardness varies15. Your supplier’s exact figure, on your water bill or a test strip, beats any table, so type it in if you have it.

Coffee. Jura rates its CLARIS Smart+ filter from 65 litres at 1–5 °dH down to 40 litres at 26–30 °dH8, and says a filter stops working after two months whatever flows through it9. We count a cup as 0.125 litres, from Siemens’ 400 cups to 50 litres; Siemens changes its EQ filter after those 50 litres or two months10. Nespresso says every three months or every 300 capsules11, KRUPS sets Dolce Gusto’s reminder at 300 cups and says every 3 months with hard water and 3 to 4 with medium12, and Moccamaster says around every 100 brews13. Machines that count for themselves ask when it is time18.

Kettle, dishwasher, humidifier. Philips and De’Longhi descale kettles monthly in hard water and every three months in soft6,7. Bosch’s dishwasher table runs from H00 to H07 by mmol/L14; Miele takes °dH directly, needs no salt below 5 °dH, and lets combi tabs replace salt below 21 °dH15. Salt has no date: refill it when the light comes on. Siemens says to clean the filters every two months16. Stadler Form’s Anticalc cartridge lasts about 360, 180, 120 or 60 litres from 4, 7, 14 or 21 °dH17.

What we leave out. We found no Swiss boiler maker or authority with a descaling interval, so the planner doesn’t give one. Philips’ numeric kettle line, and the filter figures for AquaClean, De’Longhi, Melitta and Miele, are left out because we couldn’t open them on the maker’s own page. Intervals are whole days, rounded down.

Sources

  1. 1
    Umgang mit hartem Wasser: Wasserhärte, Entkalkungsanlagen (leaflet) Kanton Solothurn · Authority · checked Oct 18, 2026
  2. 2
    Wasch- und Reinigungsmittelgesetz (WRMG), § 9 Härtebereiche Bundesministerium der Justiz (Germany) · Authority · checked Oct 18, 2026
  3. 3
    Trinkwasserqualität im Kanton Zürich nach Gemeinden und Verteilzonen (open data, attribution licence) Kanton Zürich, Gesundheitsdirektion (Kantonales Labor Zürich) · Authority · checked Oct 18, 2026
  4. 4
    Dureté du réseau d’eau potable SIG (SIG_EAU_POTABLE_DURETE), extracted 2026-10-18 Services industriels de Genève, Portail des données SITG (État de Genève) · Authority · checked Oct 18, 2026
  5. 5
    Communes genevoises (CAD_COMMUNE), extracted 2026-10-18 Portail des données SITG (État de Genève) · Authority · checked Oct 18, 2026
  6. 6
    What are the white spots on the bottom of my Philips kettle? (XC000006149) Philips · Maker · checked Oct 18, 2026
  7. 7
    How do I descale my kettle? De’Longhi UK · Maker · checked Oct 18, 2026
  8. 8
    CLARIS Smart+ filter cartridge (24232): capacity by water hardness JURA · Maker · checked Oct 18, 2026
  9. 9
    ENA Micro 9 support: changing the filter JURA USA · Maker · checked Oct 18, 2026
  10. 10
    EQ.6 plus: Wasserfilter Siemens Hausgeräte Schweiz · Maker · checked Oct 18, 2026
  11. 11
    How often should I descale my machine? Nespresso USA · Maker · checked Oct 18, 2026
  12. 12
    NESCAFÉ Dolce Gusto Genio 2: instructions for use and descaling FAQ KRUPS UK · Maker · checked Oct 18, 2026
  13. 13
    How to descale your Moccamaster coffee brewer: a step-by-step guide Moccamaster USA · Maker · checked Oct 18, 2026
  14. 14
    Dishwasher quick reference guide 9001669959 (A): water hardness settings H00 to H07 Bosch Hausgeräte · Maker · checked Oct 18, 2026
  15. 15
    Gebrauchsanweisung Geschirrspüler G 7281 / G 7288 (M.-Nr. 13 109 480) Miele · Maker · checked Oct 18, 2026
  16. 16
    Geschirrspüler: Wartung Siemens Hausgeräte Schweiz · Maker · checked Oct 18, 2026
  17. 17
    Anton ultrasonic humidifier, operating instructions (EU): anticalc cartridge and water hardness Stadler Form · Maker · checked Oct 18, 2026
  18. 18
    How to descale my Philips espresso machine (XC000004201) Philips · Maker · checked Oct 18, 2026

These are the makers’ figures for typical use. If your appliance’s manual or its own indicator says otherwise, go with that.