The water a softener treats for the average household in England and Wales measures 413 litres a day of use at 175 litres per person per day (household not on a water meter) — 2,891 litres between regenerations, at one every 7 days, per Water UK — the amount we use, England and Wales, Apr 2024 – Mar 2025, published via Discover Water (read 20 September 2026).
Source: Water UK — the amount we use, England and Wales, Apr 2024 – Mar 2025, published via Discover Water — read 20 September 2026
Why this page sizes before it prices
Size is the part of this question that can be answered from published figures: the hardness of the water, how many people are in the house, and how much water each of them uses in a day. Every one of those is published by somebody here, so the calculation below is arithmetic over other people's measurements rather than an estimate of ours.
Price is the part that cannot be answered yet. Nothing in this project has read and dated a price for salt, for water, for drainage or for the equipment itself, and until it has, the lines below say so rather than carrying a number somebody would quote back at us.
Where the sizing method comes from
The formula and the list of common capacities come from a manufacturer's sizing guide written for a different market, and that is stated beside them. What has been replaced is the part of it that is about people rather than about resin: how much water a household actually uses in a day, which is published here and is far lower than the guide assumes.
Sizing against the guide's own figure instead would push every size on this page up, and by different amounts for a metered and an unmetered household. That is the whole reason a size was not published here until the local figures had been read. Both are in the table above, beside the guide's, so the comparison is one a reader can make rather than one this paragraph asserts.
What a quotation from an installer will add
A fitted price includes work this page knows nothing about: where the rising main is, whether a drain is within reach of it, and whether an unsoftened tap has to be run to the kitchen. The regulator's guidance on the last of those is on the hub page, and it is not optional.
Nothing here is a quotation, and no installer, retailer or brand is named.
What size, at what hardness
Water at the hardness World Health Organisation Guidelines 2017 identify as scale-forming
Sized on 200 mg/L as CaCO₃.
| Household | Water use | Litres a day | Litres between regenerations | Hardness held between regenerations |
|---|---|---|---|---|
| Household on a water meter | 122 litres per person per day, for England and Wales Source: Water UK — the amount we use, England and Wales, Apr 2024 – Mar 2025, published via Discover Water — read 20 September 2026 | 287.9 litres | 2,015.4 litres | 403.1 grams as calcium carbonate |
| Household not on a water meter | 175 litres per person per day, for England and Wales Source: Water UK — the amount we use, England and Wales, Apr 2024 – Mar 2025, published via Discover Water — read 20 September 2026 | 413 litres | 2,891 litres | 578.2 grams as calcium carbonate |
Hardness figure: Drinking Water Inspectorate — Water Hardness / Hard Water, including its guidance on softening — read 20 September 2026
Lichfield
This supply runs 167.4–280.5 mg/L as CaCO₃, varying by supply zone. Sized on the top of that range, 280.5 mg/L as CaCO₃, so the unit is not undersized where the water is hardest.
| Household | Water use | Litres a day | Litres between regenerations | Hardness held between regenerations |
|---|---|---|---|---|
| Household on a water meter | 122 litres per person per day, for England and Wales Source: Water UK — the amount we use, England and Wales, Apr 2024 – Mar 2025, published via Discover Water — read 20 September 2026 | 287.9 litres | 2,015.4 litres | 565.3 grams as calcium carbonate |
| Household not on a water meter | 175 litres per person per day, for England and Wales Source: Water UK — the amount we use, England and Wales, Apr 2024 – Mar 2025, published via Discover Water — read 20 September 2026 | 413 litres | 2,891 litres | 810.9 grams as calcium carbonate |
Hardness figure: South Staffordshire Water — supply-zone water quality reports — dated 31 December 2025, read 20 September 2026
How the size is worked out
The number of people in the household, multiplied by the water each of them uses in a day, gives the litres a day the softener treats. Multiplied by the days between one regeneration and the next, that is the water it treats between regenerations; at your water's hardness, it is also the hardness the unit must hold in that time, stated here in grams as calcium carbonate.
Every size below assumes the unit regenerates once every 7 days, the interval the sizing guide cited here works to.
Regeneration interval: SoftPro Water Systems softener sizing guide — read 5 July 2026
The average UK household size was 2.36 residents per household in 2025.
Household size: Office for National Statistics — Families and households in the United Kingdom: 2025 — read 20 September 2026
What one costs to buy
No softener price has been read from amazon.co.uk, so no equipment price is published here. The shop is registered for the United Kingdom (checked on 19 September 2026), but no price has been read from it yet. A price appears here only with its amount, its currency and the day it was checked, in pounds and unconverted; a figure written without a listing behind it would be a made-up price under our own name.
Storefront: amazon.co.uk.
What one costs to run
No figure has been published here for how much salt and drain water one regeneration uses in the United Kingdom, and nobody has sourced one, so no running-cost figure is published.
Not priced here:
- salt
- regeneration-water
Do you need a water softener?
This site publishes no recommendation for or against one in the United Kingdom, at 200 mg/L as CaCO₃ or at any other figure.
- Nothing published in the United Kingdom says a softener is warranted above one hardness figure or unnecessary below another. What was looked for: a hardness figure above which a United Kingdom authority says a water softener is warranted, or below which it says one is not. Where: the Drinking Water Inspectorate's own consumer page on water hardness, which is the page that publishes the five-band scale and answers the purchase question directly.
- Drinking Water Inspectorate answers the question directly, and its answer is: "This is a matter of personal choice. If you live in a hard water area, then a softener will improve the efficiency and increase the life of domestic appliances."
- Even at the 200 mg/L as CaCO₃ its own page relays as the level at which water will produce scale, that is still the published answer. A figure of ours above which we told you to buy one would be ours alone.
- What would change this: a UK regulator, a UK standards body or a UK statutory guideline stating a hardness at which softening is recommended. The US band copy this site already ships is scaled to the USGS classification rather than to the DWI's, so it is not a substitute; the World Health Organisation figure the DWI relays is about scale forming in water, not about buying equipment.
Drinking Water Inspectorate (DWI) enforces the UK drinking water quality regulations in England and Wales. Figures it classifies or regulates on this page cover England and Wales only.
Your own supply
Sizing starts from your own water’s hardness, and this site holds a measured figure for 39 supply zones, published by 2 of 18 water suppliers. Most postcodes resolve to a supplier that publishes none, and the checker says so rather than estimating one.