Water treatment
Coffee is 98 % water, and hard water is the single most common cause of a dead machine. We compare jug filters, in-tank cartridges and mineral recipes, and cover descaling properly — including how often you actually need to.
Jug cartridge · reduces carbonate hardness · ≈ 4 weeks
Not a coffee product, and the highest-return thirty euros in this whole site. Hard water is what kills espresso machines, and a jug filter in front of the tank buys years of life for the price of a few bags of beans.
Best for: Anyone on water above roughly 150 ppm — which is most of northern Europe.
≈ $40 / £30 / 30 € (12-pack)
In-tank cartridge · ≈ 2 months
The in-tank cartridge for De'Longhi bean-to-cup machines. It does what an in-tank filter does — reduces the hardness reaching the boiler with no habit to maintain — at the manufacturer's price.
Best for: Any De'Longhi bean-to-cup owner who will not reliably fill from a filter jug.
≈ £25 / 28 € (2-pack)
In-tank cartridge · up to 5,000 cups
Philips claims up to 5,000 cups without descaling if the filter is replaced on schedule. That is broadly true and entirely conditional — miss a replacement and the claim expires with it.
Best for: Philips and Saeco bean-to-cup owners on medium to hard water.
≈ £30 / 32 € (2-pack)
Jug cartridge · adds magnesium · ≈ 4 weeks
Unlike a standard filter, this one adds magnesium back after removing hardness. Magnesium is what pulls flavour out of coffee, so the cup gets sweeter rather than just safer for the machine.
Best for: Someone already filtering who wants the water to improve the coffee, not just protect the machine.
≈ $45 / £35 / 38 € (6-pack)
A cartridge's service life decides how often it is replaced, and a spent cartridge filters nothing while staying in place.
In very calcareous water, filtration costs less than descaling cycles — and infinitely less than a repair.
Enormously — it is more than 98 % of the cup. The same coffee made with two different waters gives two markedly different results.
Medium hardness, neither very soft nor very calcareous. Water that is too soft gives a flat coffee; very hard water masks the aromas and scales the machine.
It reduces hardness and improves taste for a modest cost. On an expensive machine in very hard water, a dedicated cartridge protects better.
At the stated volume or duration, whichever comes first. A spent cartridge no longer filters and can release what it has held.
Some lightly mineralised waters work very well. It is mainly a recurring cost and bulk for a gain filtration often reaches.
It stretches it a great deal without removing it. No domestic filtration retains all the minerals responsible for scale.
For a steam appliance it is often recommended. For coffee, no: without minerals the extraction is incomplete and the cup hollow.
Water is the most important and least examined ingredient in coffee. In a calcareous region, filtering costs less than descaling and far less than a repair — but aiming for fully demineralised water degrades the cup as much as limescale does.
Only the specifications at least four models out of five state. A column that is more empty than full compares nothing.
| Model | Price | Fits | Life | Type |
|---|---|---|---|---|
| De'Longhi DLSC002 Water Filter | 25 $ | De'Longhi ECAM and Magnifica ranges | ≈ 2 months / 50 L | In-tank cartridge |
| Philips AquaClean CA6903 | 30 $ | Philips and Saeco espresso machines | ≈ 3 months or by cup count | In-tank cartridge |
| BRITA Maxtra Pro Pure Performance | 40 $ | All BRITA Maxtra and Maxtra+ jugs | ≈ 4 weeks / 100 L | Jug cartridge |
| BWT Magnesium Mineralized Water cartridges | 45 $ | BWT jug systems | ≈ 4 weeks / 120 L | Jug cartridge |
Specifications: manufacturer sheets and Amazon product pages. Prices and availability: Keepa. No product on this site has been physically tested.
Most recent revision in this category: August 8, 2026.
