How much does a water softener cost, and is it worth it?
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Part of our hard water guide
Your kettle is furred and a softener quote is on the table. What do UK consumer and regulator sources say it costs, and when does it make sense?
Short answer: Which? says to expect to spend around £300 to £1,500 on a water softener, plus salt at £20 to £30 for a 25 kg bag. The Drinking Water Inspectorate (DWI) calls fitting one a matter of personal choice. By our reading of its bands, softening matters mainly where water is hard, at 200 mg/l or more.
By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026
Whatever the quote says, the useful first number is how hard the water is at your own tap, and you can check that in a minute with a 20-in-1 test strip. The costs come first.
How much does a water softener cost?
Which? says to expect to spend around £300 to £1,500, depending on the size and type of system, plus salt. That is from its buying guide dated 17 September 2026. It does not say whether fitting is included, so check each quote.
| Cost | Figure | Source |
|---|---|---|
| A softener | Around £300 to £1,500 | Which?, 17 September 2026 |
| Retailer prices | Amazon £300 to £600, B&Q from about £400, Screwfix £500 to £1,000, Toolstation £500 to £700, Wickes £540 to £700 | Which?, same guide |
| Fitting | No official or consumer-body figure in the sources we read | Which? gives none |
| Salt, 25 kg bag | Typically £20 to £30, for the salt tablets most systems use | Which?, same guide |
| Salt top-ups | As a general rule every two to four weeks | A trader quoted by Which? |
Which? gives no yearly salt figure, and the trader it quotes says refill frequency depends on the model, your water hardness and household use. The same trader warns that cheap units may need replacing within a handful of years and can use more salt.
How does a water softener work?
It swaps the calcium and magnesium that make water hard for sodium, a process called ion exchange. The DWI describes it that way, and Which? explains the parts. Hard water passes through a tank of resin beads, where the swap happens. When the resin is used up, the unit regenerates by flushing it with a strong salt solution from a second tank, which is why you top up the salt.
Which? says timed models regenerate on a fixed schedule and are generally cheaper upfront but can be less efficient, while metered models regenerate after a set volume of water and help reduce waste. Our softener guide goes through the process, and our filter and softener comparison covers the alternatives.
How often should you service a water softener?
No UK regulation in the sources we read sets an interval. The DWI says to follow the manufacturer's advice on cleaning and maintenance, and that some units need regular backwashing and salt. It says it is sensible to consider a service agreement, and the DWI's hardness page advises a maintenance contract so the softener keeps operating correctly and does not become a hygiene hazard.
A trader quoted by Which? says cheap units might also need expensive annual servicing. The interval for your unit is in its manual, and our servicing guide has more.
Is it worth having a water softener?
The DWI says it is "a matter of personal choice". In a hard water area it says a softener will improve the efficiency and increase the life of domestic appliances, make lathering easier and reduce tide marks on sanitary ware. It also cites World Health Organization guidance that water at 200 mg/l or more, as calcium carbonate, will produce scale. Which? says a softener may reduce spending on maintenance, cleaning products and appliance repairs over time. None of the sources we read (Which?, the DWI and the regulations listed below) gives a figure for how many years that takes to cover the cost.
The DWI also lists the other side.
- Keep one unsoftened tap. Softeners replace hardness with sodium, and the DWI says some can add significantly to the sodium in drinking water. The Water Supply (Water Quality) Regulations 2016, which apply to water companies in England, set a limit of 200 mg of sodium per litre at consumers' taps, and the DWI says a softener may risk breaching it, so it advises an unsoftened kitchen tap for drinking and cooking. See can you drink water from a water softener.
- Taste and plumbing. A softener may alter the taste and smell of the water, the DWI says, and softened water may be aggressive to plumbing. It says artificially softened water should not be used to make up baby feeds.
- Where it goes. The DWI says fitting a softener just before the hot water tank or boiler is more economical for preventing limescale than softening the whole supply.
What one reader found
In a June 2025 MoneySavingExpert forum thread, one member said their softener cost around £2000 including installation, in a two bedroom flat with two bathrooms. They said it made a big difference to the washing machine and dishwasher and a noticeable one in the shower, and called it "possibly the best decision we ever made". That is one household's view, not a typical cost. The person who started the thread had been quoted £2,000 to £5,000 for a two bedroom house, against £500 to £800 for units online, so it is worth asking whether a quote includes fitting. Shared on the MoneySavingExpert Forum.
Why might my tap differ from the area hardness figure?
The DWI says hardness varies with local geology, and its map of typical hardness in England and Wales does not show areas with local variation, so for an accurate measurement it says to ask your water company. A water treatment trader quoted by Which? says that for most people in hard water areas the figure is between 250 and 320 mg/litre. He adds that there are small pockets of UK water above 390 mg/litre.
“If you're weighing up a softener quote, I'd measure the water at the tap you'd actually be softening rather than leaning on the area figure alone. The area figure is an average, and what comes out of your own tap can differ from it.”
A test strip read at the tap you would soften gives you a band to set beside the quote before you spend £300 or more. Our postcode hardness guide shows where to find the company's figure.
What are the rules for fitting one?
In England and Wales, tell your water company first. Regulation 5 of the Water Supply (Water Fittings) Regulations 1999 requires notice to the water undertaker, and its consent, before anyone installs a water treatment unit that produces waste water or needs water for regeneration. That fits a salt-regenerated softener, in our reading. The company can refuse or set conditions within ten working days, but must not refuse unreasonably, and if it says nothing in that time, consent counts as given. We have not checked the rules in Scotland or Northern Ireland.
The DWI advises a qualified plumber, a reputable supplier and a check with your water company that the device meets the regulations. It warns against buying from door-to-door sellers, particularly those offering to test your water to demonstrate a problem. For building work, Schedule 1 of the Building Regulations 2010 (marked as covering England and Wales) requires wholesome water at drinking points and kitchen sinks, while softened wholesome water is allowed to basins, baths and showers.
How can I check whether softening is relevant at my tap?
Test the water. The WaterKit Water Test Kit has a hardness pad with colour steps at 0, 25, 50, 100, 250 and 425 mg/L. Fill a clean glass or cup, dip one strip, wait 30 to 60 seconds and match the pads to the chart. You can also scan the QR code on the chart, or enter the colours at our results checker, with no app or account. The DWI's bands are in mg/l as calcium carbonate. We have not confirmed that the chart's steps are on the same basis, so comparing the two directly is our reading of the chart. The last column is our view, not the DWI's.
| Pad reading (mg/L) | DWI band (mg/l) | Is softening relevant? (our view) |
|---|---|---|
| 0, 25 or 50 | Soft (up to 100) | No, there is little limescale to remove |
| 100 | Top of soft, slightly hard above it (100 to 150) | Rarely |
| 250 | Hard (200 to 300) | Worth pricing up |
| 425 | Very hard (over 300) | Where a softener makes the biggest difference |
There is no step between 100 and 250, so water that is really 150 to 200 will show as a nearby step and the pad cannot tell you which side of the line you are on. A fall from the 250 step to the 25 step is plain to see, but a smaller fall inside one step will not show. We do not claim the strip for sodium, so it cannot tell you how much sodium a softener adds. Our hardness testing guide covers the method.
A before-and-after test. Test the tap you plan to soften and your kitchen tap before fitting, and note each step. After fitting, run the softened tap for a minute, then test again.
- The softened tap should drop to a lower step. How far depends on the unit and its settings, so check the manual.
- The kitchen drinking tap should stay where it was. If it has dropped, it may be softened, which the DWI advises against.
- If the softened tap later creeps back up the chart, check the salt and the manual. That is our suggestion, not a servicing rule.
The area figure is an average, and the DWI says its hardness map does not show areas with local variation, so your own tap may read differently from the figure for your postcode. The hardness pad is the one that matters here, and a reading that drops a step or more after fitting points to the softener working at that tap, while a kitchen drinking tap that has also dropped points to it being softened too. Best pack: 20 strips, enough to test two taps before fitting and the same two after, with strips left for re-checks, £5.99 (or £10.99 with a bacteria test), with free 2nd Class delivery on every order. See the kit
Your water softener questions
How much does a water softener cost?
Which? says to expect to spend around £300 to £1,500 to buy one, plus salt at £20 to £30 for a 25 kg bag. The sources we read give no figure for fitting.
How does a water softener work?
By ion exchange. Resin beads swap the calcium and magnesium in your water for sodium, and a salt solution recharges the resin, according to the DWI and Which?.
Is it worth having a water softener?
The DWI says that is a matter of personal choice. The benefits it lists apply in hard water areas.
How often should you service a water softener?
No UK regulation in the sources we read sets an interval. The DWI says to follow the manufacturer's advice and consider a service agreement. See our servicing guide.
Can you drink water from a water softener?
The DWI advises keeping an unsoftened kitchen tap for drinking and cooking. Which? gives the same advice, and says the AIWSE states that people on a low-sodium diet should not drink it.
Sources
- Which?, How to buy the best water softener (17 September 2026; unit prices, retailer prices, salt price, top-up interval, cheap units, timed and metered models, trader comment on hardness, AIWSE low-sodium statement; read 29 October 2026).
- Drinking Water Inspectorate, Domestic water filters and softeners (undated page; ion exchange, sodium, unsoftened tap, taste, baby feeds, maintenance and service agreement, qualified plumber, door-to-door sellers; read 29 October 2026).
- Drinking Water Inspectorate, Water hardness / hard water (undated page; hardness bands, local variation and the map, WHO 200 mg/l scale figure, personal choice, appliance benefits, boiler or hot water tank option, maintenance contract, plumbing; read 29 October 2026).
- The Water Supply (Water Fittings) Regulations 1999, regulation 5 (notice and consent for treatment units that need water for regeneration; England and Wales; read 29 October 2026).
- The Water Supply (Water Quality) Regulations 2016, Schedule 1 (sodium 200 mg Na/l at consumers' taps; these Regulations apply in England; read 29 October 2026).
- The Building Regulations 2010, Schedule 1, Part G1 (wholesome water at drinking points and kitchen sinks; softened water to basins, baths and showers; read 29 October 2026).
- MoneySavingExpert Forum, How much should I be paying for having a water softener supplied and fitted? (thread of 3 to 4 June 2025; one member's reported cost and experience, paraphrased; a forum post, not an official source; read 29 October 2026).
- WaterKit, Water Test Kit (20-in-1 strip, 30 to 60 second read, 20 strips £5.99, free 2nd Class delivery on every order) and results portal (hardness pad steps 0, 25, 50, 100, 250, 425 mg/L). The strip-chart column and the matching to the DWI bands are WaterKit's own reading of the colour chart steps.
Contains public sector information licensed under the Open Government Licence v3.0.