Can you drink softened water?

An ion-exchange softener replaces calcium and magnesium with a small amount of sodium, so softened water carries more sodium than the supply it came from. The usual arrangement is to leave one tap - normally the kitchen cold tap - unsoftened for drinking and for filling a kettle, and that tap is also what a plumber will use for anything on a low-sodium diet or for making up baby formula.

Does a water softener remove limescale that is already there?

Softened water will gradually dissolve existing scale in pipework and appliances rather than adding to it, so systems tend to clear over months rather than immediately. It is not a descaler and it will not strip a badly furred element on its own.

How much salt does a softener use?

It depends on the hardness of the incoming water and how much water the household uses, which is why no single figure is meaningful. The unit regenerates on a cycle and the salt is topped up when the tank runs low - a routine household task rather than a service visit.

A softener is plumbed into the incoming main after the drinking-water take-off, and it needs a drain connection for the regeneration cycle and usually a power socket. Some units are designed for competent DIY installation; most are fitted by a plumber or by the supplier.

Are water softeners worth it?

A water softener does one thing: it takes the calcium and magnesium out of the incoming water so that limescale stops forming. Whether that is worth the outlay depends on how hard the water is, how much of the house runs on hot water, and how long the household intends to stay.

How the common type works

The standard domestic unit is an ion-exchange softener. Water passes through a resin that holds sodium ions; the resin grabs the calcium and magnesium and releases sodium in their place. Periodically the resin is flushed with a strong brine solution to reset it — the regeneration cycle — and that is what the salt in the tank is for.

Two consequences follow, and both matter more than the mechanism. The unit needs a drain for the regeneration water, and it needs salt topping up. A softener is not a fit-and-forget appliance; it is one with a small standing consumable.

What it does, and what it does not

It does

Stop new limescale forming in pipework, cylinders and heating elements
Gradually clear scale that has already built up
Cut the amount of soap, shampoo and detergent needed for a lather
Take the scale marks off taps, screens and glassware

It does not

Filter the water or improve its taste — that is a different device
Remove chlorine, metals or anything a filter is bought for
Make hard water safe — it already was
Run without salt and a drain

That last distinction is the one most often blurred in the buying process. Softening and filtering are separate jobs done by separate machines. A household that wants better-tasting drinking water wants a filter; a household that wants its kettle to stop furring wants a softener; a household that wants both needs both.

How to judge whether it pays

There is no universal answer, and any figure quoted as one should be treated with suspicion. The variables that actually move it:

How hard the incoming water is. The harder it is, the faster the case builds. Softeners are a poor purchase in a soft-water area and an obvious one at the top of the hardness range.
What the hot-water system is. A house with a combi boiler, an unvented cylinder and multiple showers has more to protect than a small flat.
How long the household will be there. The purchase is capital; the benefit accrues over years. It suits a home someone intends to keep.
The running cost. Salt, the water used in regeneration, and occasional servicing. Small individually, permanent collectively.

On brands, and why there is no table here yet

The names people search for most are a handful of established manufacturers, and a comparison between them is exactly what a page like this should carry. Water Pages has not tested them and has no independent evidence to rank them on, so it is not going to publish an order dressed up as a verdict. When there is a basis for a comparison it will appear here, and it will say what the basis was.

Common questions

Can you drink softened water?: An ion-exchange softener replaces calcium and magnesium with a small amount of sodium, so softened water carries more sodium than the supply it came from. The usual arrangement is to leave one tap - normally the kitchen cold tap - unsoftened for drinking and for filling a kettle, and that tap is also what a plumber will use for anything on a low-sodium diet or for making up baby formula.
Does a water softener remove limescale that is already there?: Softened water will gradually dissolve existing scale in pipework and appliances rather than adding to it, so systems tend to clear over months rather than immediately. It is not a descaler and it will not strip a badly furred element on its own.
How much salt does a softener use?: It depends on the hardness of the incoming water and how much water the household uses, which is why no single figure is meaningful. The unit regenerates on a cycle and the salt is topped up when the tank runs low - a routine household task rather than a service visit.
Do I need a plumber?: A softener is plumbed into the incoming main after the drinking-water take-off, and it needs a drain connection for the regeneration cycle and usually a power socket. Some units are designed for competent DIY installation; most are fitted by a plumber or by the supplier.

Already have one? Block, tablet or granular salt — what the difference actually is.