A filter reduces what its manufacturer declares it reduces. This site reports that declaration and stops there; it makes no claim about health, and none of these products is presented as making water safe that was not.
The three technologies, and what each addresses
Activated carbon adsorbs chlorine and the taste and odour that come with it, and some organic compounds. It is what most under-sink and tap filters are.
Ceramic or sediment cartridges catch particles down to a stated micron size. That is a physical filter, and the micron figure is the whole specification.
Reverse osmosis pushes water through a membrane and removes far more, including dissolved minerals. It runs slowly, it wastes water to drain, and it needs a tank and its own tap.
How to compare two of them honestly
By declared reductions, stated capacity in litres, and cartridge price divided by those litres. That last division is usually more revealing than any comparison of the housings — a cheap unit with expensive cartridges costs more within a year.
The context that matters
In every country this site covers, mains water is already regulated as drinking water. A filter here is bought for taste, for particles after building work, or for scale — not to make water potable.
This does not replace the manufacturer's own instructions. Every dimension, thread size, flow rate, operating pressure, water seal depth and load figure on this page is reported from the manufacturer's own documentation, with its unit written as published, and named as such — none of it is measured here. A flow rate is reported with the pressure the manufacturer measured it at, and is never converted to another pressure, because no conversion exists. And the second statement repeated rather than assumed: a water softener treats limescale and is not a health product — softened water carries more sodium, not less. A filter reduces what its manufacturer declares it reduces; no benefit for skin, hair or health is claimed here, and drinking water quality is a matter for your supplier.
Questions people actually ask
Do filters remove limescale?
Carbon filters do not. Some cartridges add a scale-inhibiting media that the maker declares separately, and softeners work on a different principle entirely. Read what the maker declares rather than assuming a filter covers everything.
How do I know when to change a cartridge?
By the litres or months the manufacturer states, not by taste — taste changes late. Some units have a mechanical or electronic indicator, and that is what it is for.
Last reviewed 5 September 2026