A softener exchanges the calcium and magnesium in your water for sodium, which is why kettles and shower screens stop furring. That is what it does, and this site claims nothing beyond it.
How the exchange works
Water passes through a resin bed that holds sodium ions and swaps them for the calcium and magnesium it meets. When the resin is saturated it is regenerated with a brine solution made from salt, and the displaced hardness goes to the drain.
What it is not
It is not a filter and not a purifier. It does not remove chlorine, bacteria, metals or anything else; softened water carries more sodium than it did, not less. In every country this site covers, mains water is already regulated as drinking water, and questions about drinking it are for your supplier and your doctor rather than for a comparison page.
What decides which one you need
Your water hardness, which your supplier publishes, and your household’s daily consumption. Every capacity in this family is quoted against a hardness, and without yours the numbers cannot be compared at all.
The running cost
Salt, and how much of it depends on whether the unit regenerates on a timer or on a water meter. The metered ones cost less to run for the same water.
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
Is softened water safe to drink?
That is a question for your water supplier and, if it matters medically, your doctor — not for this site. What can be said plainly is that softening adds sodium and removes hardness, and that many installations keep one unsoftened tap for drinking.
Will a softener remove existing limescale?
Not directly. It stops new scale forming; existing deposits in a kettle or on a screen still have to be descaled once. What people notice is that they stop coming back.
Last reviewed 5 September 2026