Shower filter vs water softener: which does your home need?

The shower filter vs water softener question comes down to which problem you have. A water softener deals with hard water and limescale by swapping calcium and magnesium for sodium. A filter shower head is designed to reduce free chlorine; it does not soften water or remove limescale.

Below, we explain what makes water hard, how to check your area, what each device does and does not do, and which to choose in three common situations. For the wider picture, see our complete, honest guide to filter shower heads in the UK.

We sell a filter shower head, not a softener, so every figure here links to its source, and we say plainly when a softener is the better fit.

Shower filter vs water softener: the short answer

A shower filter and a water softener solve different problems. A water softener treats hardness, the dissolved calcium and magnesium behind limescale, while a filter shower head is designed to reduce free chlorine.

Hardness and chlorine are separate questions. Hardness comes from the rocks your water passes through. Chlorine is added on purpose, to disinfect the water and protect it in the pipes. The Drinking Water Inspectorate (DWI) says water companies typically keep that residual at 0.5 mg/l or less.

So start by naming your problem. Scale in the kettle and tide marks on the basin point to hardness. A chlorine smell in a hot shower points to chlorine. Some homes have both, and then both tools can make sense, each doing its own job.

What makes water hard?

Hard water is caused by dissolved calcium and magnesium, which rainwater picks up as it filters through rocks. How hard your water is depends on local geology, and the DWI grades it in five bands.

The DWI's guide to water hardness measures hardness in mg/l as calcium carbonate:

Geography drives the pattern. Discover Water, which reports on water companies in England and Wales, says water is generally harder in the south and becomes softer moving north.

Yorkshire Water explains that hard water typically comes from chalk and limestone, and soft water from moorland.

Hardness matters mainly because of scale. The DWI, citing the WHO's 2017 guidelines, says water of 200 mg/l or more will produce scale. Scale on heating elements shortens their life and makes appliances less efficient, the DWI adds. In the hard and very hard bands, limescale tends to become a regular chore.

Boiling is why kettles scale up. The DWI explains that temporary hardness, from calcium and magnesium carbonates and bicarbonates, comes out of the water as scale when it is boiled.

How to check if your area has hard water

The quickest way to check if your area has hard water is your water company's postcode checker or water quality report. The DWI publishes a map of typical hardness, but says to ask your water company for an accurate figure, because the map misses local variation.

1. Find your water company: its name is on your water bill.
2. Search its website for "water quality" or "hardness" and enter your postcode. Yorkshire Water, for example, has a postcode checker that shows how hard or soft your water is.
3. Or ask for the free drinking water quality report for your home, which water companies provide on request.
4. Compare the figure with the DWI bands above.

The report tip comes from the DWI's advice on home filters and softeners, which suggests getting one before buying any water treatment product.

You can also read the signs at home. The DWI and Discover Water list these everyday clues:

• Scale or furring in the kettle and on heating elements.
• Tide marks on basins, sinks, baths and toilets.
• Less lather from soap, washing-up liquid and washing powder.
• A scum on the surface of tea.

There is no UK standard for hardness. The DWI says the UK drinking water regulations set none for hardness, calcium or magnesium. Hard water is a property of where you live, not a failed test.

What does a water softener do?

A water softener reduces hardness by ion exchange: it replaces the calcium and magnesium in your water with sodium. The DWI says the benefits include less scale in hot water systems, better lather and more efficient washing machines and dishwashers.

A softener is plumbed into your supply, either for the whole house or just before the hot water tank or boiler. The DWI notes that softening only the water going to the tank or boiler is a more economical way to prevent limescale than softening the whole supply. Whether to fit one at all is, in the DWI's words, "a matter of personal choice".

Three points of care come with a softener:

• Keep an unsoftened kitchen tap for drinking and cooking. The DWI advises this because most softeners work by replacing hardness with sodium.
• Have it fitted properly. The DWI advises a qualified plumber, and says any product must meet regulation 4 of the Water Supply (Water Fittings) Regulations 1999. Under it, every water fitting must be of an appropriate quality and standard, and suitable for the circumstances in which it is used.
• Plan for upkeep. The DWI says softeners need regular backwashing and fresh salt, and suggests considering a service agreement.

Renters need permission first. Shelter England advises tenants not to make improvements without the landlord's permission, and to get the agreement in writing before starting. Plumbing in a softener is likely to count, so speak to your landlord directly: Shelter says an agent cannot usually agree to improvements alone.

What a shower filter does, and doesn't do

A filter shower head is designed to reduce free chlorine. A shower filter does not soften water, remove limescale or take out calcium and magnesium, so your water's hardness stays the same.

Free chlorine is one form of the disinfectant residual that water companies keep in tap water, and it is there by design. Our explainer on why UK tap water contains chlorine, and how much covers the detail. Hardness is minerals; chlorine is disinfection.

Limescale does not skip the shower. In a hard water area, any shower head, filtered or not, can build up scale on its face and jets over time. Clean yours as its maker's instructions say, and do not expect a filter to prevent scale.

So if you are looking for a shower filter for hard water, the honest answer is that a filter designed to reduce free chlorine will not change your water's hardness. A softener or regular descaling deals with scale.

What a filter shower head offers is a preference: some people would rather shower with less free chlorine. For what the evidence does and does not show, read do shower filters work? What the evidence really says.

The difference between a shower filter and a water softener

The difference between a shower filter and a water softener is what each one targets: free chlorine at the shower, or hardness in your supply. The table sets them side by side.

Which one do you need? Three common situations

Choosing between a shower filter and a water softener depends on the problem you want to solve. Limescale points to a water softener or regular descaling; a preference for less free chlorine in the shower points to a filter shower head.

You are fighting limescale

A water softener is the tool for hardness, or you can keep on top of scale by descaling. Discover Water's kettle method: half fill the kettle, add two tablespoons of white vinegar and leave it for four hours. Then empty it, rinse, and repeat as needed. Many dishwashers have a built-in softener that needs regular dishwasher salt.

The DWI also notes that some activated carbon jug filters contain ion exchange resin that may reduce scale in kettles. They do not change the water's permanent hardness. A filter shower head will not help with limescale.

You would rather shower with less free chlorine

A filter shower head is designed for this; a softener's job is hardness. A handheld filter head needs a shower with a hose outlet. If you have an electric shower, check your shower manufacturer's manual before changing the head.

You want both

Then both can make sense, because they do different jobs and one does not replace the other. A softener on the supply handles hardness; a filter shower head at the shower is designed to reduce free chlorine. Keep an unsoftened kitchen tap for drinking and cooking, as the DWI advises.

Where Waterhush fits

Waterhush fits the chlorine question, not the hardness one. The Waterhush Shower Kit reduces free chlorine; it is not a water softener and does not remove limescale.

The kit is a round handheld head with 10 jets numbered 01 to 10 and the cartridge already fitted in the handle. The cartridge includes four filter media: calcium sulfite, vitamin C, KDF and carbon. The full kit specifications list everything in the box, including what it does not do.

The head comes on its own 1.5 m hose, so it replaces your existing handheld head and hose rather than being plumbed in. Renters can keep the old head and hose to put back when they leave. Ask your landlord and check your tenancy agreement first, and read whether you can change a shower head when you rent.

Fit comes first. The kit needs a shower with a hose outlet, and electric showers are not confirmed, so check your shower manufacturer's manual.

We have no confirmed thread size, water pressure or flow figures, so check the fit before you buy. Is it right for your shower? Check in three questions.

The bottom line

A shower filter and a water softener do different jobs. A water softener treats hardness and limescale; a filter shower head is designed to reduce free chlorine and does not soften water.

Start by checking your hardness with your water company. If limescale is the problem, look at a softener or regular descaling; if you would rather shower with less free chlorine, a filter shower head is designed for that.