Do water filter jugs actually work?
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Part of our filters and softeners guide
The jug on the worktop promises better taste and less limescale. What do the regulators and independent testers say it does, and how can you see what it changes at your own tap with a 20-in-1 test strip?
Short answer: Yes for chlorine taste and some kettle scale, according to the Drinking Water Inspectorate (DWI). It says activated carbon jugs suit taste and odour, water companies typically hold chlorine to 0.5 mg/l or less, and resin beads alter only "temporary" hardness. Which? says the best jugs improve taste by softening hard water.
By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026
Do water filter jugs actually work?
For the jobs they are built for, yes, and those jobs are few. The DWI says removing objectionable taste and odour is the most common reason people buy a filter. You can see what a jug changes at your own tap by dipping a 20-in-1 test strip in tap water and then in jug water, as set out at the end of this guide.
| What you want | What the sources say a jug does |
|---|---|
| Less chlorine taste or smell | The DWI says to choose activated carbon. Scotland's Drinking Water Quality Regulator (DWQR) and Welsh Water both say filters can remove chlorine |
| Less kettle scale | The DWI says some carbon jugs also hold ion exchange resin beads that alter "temporary" hardness, so tea scum and kettle scale may be reduced. Which? says the best jugs improve taste by softening hard water |
| Permanent hardness | The DWI says these devices do not alter it |
| Removing contaminants | Which? says it does not test jugs for filtering harmful contaminants. The DWI says public supplies in England and Wales are regularly tested and need no extra home treatment as a health protection measure |
Our guide on whether to filter your tap water covers lead and fluoride.
How does a water filter jug work?
You pour water into the top and it passes through a cartridge. The DWI describes jug filters as stand-alone, with no connection to the water supply, and tells buyers who want better taste to pick a cartridge containing activated carbon. Some carbon jugs add resin beads, which it says change only temporary hardness. That is the hardness due to calcium and magnesium carbonates and bicarbonates, which boiling removes as scale.
Welsh Water says jug filters are designed to remove chlorine. The DWI and Welsh Water both say tiny black particles in the water come from the cartridge. The DWI says they are carbon, and Welsh Water says it means a fault and the cartridge needs replacing.
Does filtered water taste different, and why can it taste odd?
It can. The DWI says tap water tastes different across regions because of hardness and residual chlorine, and a jug can change both. A covered glass jug of tap water in the fridge also lowers chlorine taste, according to the DWI, and it calls that more cost-effective than a carbon filter. Scottish Water and Welsh Water give the same tip, and our chlorine guide has more.
On odd tastes, the DWI says plumbing, fittings and appliances are the most common cause. Water sitting in copper, iron or galvanised pipes or tanks can pick up a metallic or bitter flavour, which it says is more noticeable when warmed, and flushing the tap removes it. The DWQR names tap washers and appliance hoses that are not British Standard approved, and a kettle if the taste appears only in hot drinks.
Why does my water filter jug go green?
Welsh Water's jug leaflet says bacteria or algae can grow if the maker's guidelines are not followed, and that some customers have reported green material in their jug filters. It explains that jugs remove the chlorine added to stop micro-organisms regrowing, and that sunlight promotes algae in water without chlorine.
The DWI says a carbon cartridge not changed to the maker's schedule ceases to be effective and may leach other chemicals or bacteria. Welsh Water advises keeping filtered water out of direct sunlight and in the fridge, using it within 24 hours, and washing the jug but not the filter. Our guide on how often to change a water filter covers schedules.
Why might my tap not match the area figure?
The area figure is an average. Your tap can differ because chlorine, hardness and plumbing vary from house to house. Welsh Water says its zone reports summarise all the samples taken in a zone each year and are not property specific.
- Distance from the works. The DWI and Welsh Water say homes near a treatment works or chlorine booster station can get slightly more chlorine than homes further down the network.
- New mains. Scottish Water says chlorine can be more noticeable after a nearby main is replaced, because the new pipe does not absorb it as the old one did.
- Local hardness. The DWI says its hardness map does not show local variation, and to ask your water company for an accurate figure.
- Your own pipes. The DWI says water picks up traces from plumbing and fittings, that hot tap water can carry elevated metals such as copper, and that bathroom cold taps may be fed from a tank not suited to drinking.
A strip at your kitchen cold tap, and again at another tap, shows whether chlorine and hardness differ inside your own home.
“I wouldn't lean on the area figure alone, because it's an average and your own tap can sit a little either side of it depending on your pipework and how far you are from the works. A quick check at your kitchen cold tap is a sensible way to see what's actually coming out at your place.”
What one reader found
A poster on The Homebrew Forum UK said they live in Derbyshire, where they describe the water as on the hard side. They run their tea, mash and drinking water through a filter jug and said the filtered tap water tastes much better. They were asking whether to use it for their first home brew too. It is one person's view of taste, and the post gives no measurements. Shared on The Homebrew Forum UK.
How can I check what my jug changes at home?
Use three strips. Run the cold kitchen tap for a minute or two first, as Welsh Water advises. Fill a clean glass with tap water, dip one strip, wait 30 to 60 seconds and match the pads to the chart, or enter the colours in our results portal. Then repeat with water freshly filtered through the jug. Do a third with tap water that has stood a couple of hours in a covered jug in the fridge, which Scottish Water says helps chlorine dissipate. The free checker needs no app or account, and the QR code on your chart opens it.
The strip has limits. It cannot read lead at the UK limit, so a clear lead pad says nothing about whether a jug reduces it, and our lead pipes guide covers that instead. The chart reads in set steps, so a change between two steps will not show, and a strip result is not a legal sample. The optional rapid coliform test is a presence screen, read after 24 to 48 hours, and does not pick up every kind of bacteria. If you add it, run one on tap water and one on jug water. A positive on the jug only indicates coliforms in the jug water, a prompt to clean the jug and change the cartridge as the maker instructs, then test again. If the tap sample is positive too, contact your water company.
| Pad | Chart steps (mg/L) | What the three strips can show |
|---|---|---|
| Free and total chlorine | 0, 0.5, 1, 3, 5, 10, 20 | The DWI says typical levels are 0.5 mg/l or less and the first step is 0.5, so many taps read 0 or 0.5 and leave little to compare. A tap at 0.5 or 1 and a jug at 0 indicates the jug took it below the first step. If the fridge-stood sample also reads 0, a plain covered jug did the same, as the DWI suggests it can |
| Hardness | 0, 25, 50, 100, 250, 425 | A tap at 100 or more and a jug one step lower indicates the jug lowered hardness. The pad does not separate temporary from permanent hardness, and we have not confirmed its unit matches the DWI's calcium carbonate bands, so any comparison with them is ours |
The area figure is an average, and Welsh Water says its zone reports are not property specific, while the DWI says homes nearer the works can get slightly more chlorine, so your own tap may differ. The pads that matter here are free and total chlorine and hardness. A tap at 0.5 or 1 with the jug at 0 indicates the jug took chlorine below the first step, and a jug one hardness step below a tap at 100 or more indicates it lowered hardness. Best pack: 20 strips, enough for 6 rounds of three strips (tap, jug and fridge-stood), £5.99 (or £10.99 with a bacteria test), with free 2nd Class delivery on every order. See the kit
Your water filter jug questions
How does a water filter work?
In a jug, water passes through a cartridge. The DWI says to choose one containing activated carbon for taste and odour, and notes some also hold ion exchange resin beads.
What does a water filter do?
The DWI says removing taste and odour is the most common reason to buy one.
Are water filter jugs worth it?
Which? says the best jugs improve taste by softening hard water. For chlorine taste alone, the DWI says a covered glass jug in the fridge is more cost-effective, and Welsh Water calls a filter purely a personal choice.
What does a water filter jug do?
Chlorine taste and, with resin, some temporary hardness. The DWI says permanent hardness is unchanged.
What does a water filter remove?
It depends on the type. Our filters and softeners guide sets out the main kinds.
Does filtered water taste different?
It can. Which? says the best jugs improve taste, and the DWI says taste varies with hardness and chlorine, which a jug can change.
Why does filtered water taste weird?
The DWI says plumbing, fittings and appliances are the most common cause of strange tastes. It also warns that a cartridge left unchanged may leach other chemicals or bacteria.
Why does filtered water taste sweet?
In the sources we read, we found no official guidance on this.
Why does my filtered water taste like metal?
The DWI and Welsh Water say copper, iron or galvanised pipes and tanks can give water a metallic or bitter taste, and that flushing the tap removes it.
How to use a water filter jug
Welsh Water says to run the cold tap for a minute or two, keep filtered water out of direct sunlight, refrigerate it and use it within 24 hours. It also says to wash the jug but not the filter. Our guide to filtering tap water at home has more.
How long does a water filter jug last?
The sources we read give no set interval. The DWI says to change the cartridge in line with the maker's instructions or it will cease to be effective.
Sources
- Drinking Water Inspectorate, Domestic water filters and softeners (undated page; jugs stand alone; manufacturers' claims; taste and odour the most common reason; activated carbon; cartridge changes, bacteria and leaching; black particles; covered jug in the fridge; no additional treatment needed as a health protection measure; read 29 October 2026).
- Drinking Water Inspectorate, Chlorine (typical residual 0.5 mg/l or less; higher near the works; fridge jug and 24 hours), Water hardness (jugs with ion exchange resin alter temporary hardness, not permanent hardness; map does not show local variation) and Taste and odour in drinking water (plumbing the most common cause; metallic or bitter flavour; hot taps and bathroom tanks); all undated pages, read 29 October 2026.
- Drinking Water Quality Regulator for Scotland, Chlorine (domestic filters that remove chlorine, maintained to the maker's instructions) and Taste and smell (medicinal or metallic taste from non-approved plumbing items and kettles); both undated, read 29 October 2026.
- Dŵr Cymru Welsh Water, Water quality in the home (filters and chlorine; the jug steps; zone reports not property specific), Strange taste or smell to my water (chlorine near works and in winter; metallic taste from home plumbing) and Customer information INFO 0080, Jug filters (undated leaflet; bacteria, algae, green material, black particles); all read 29 October 2026.
- Scottish Water, Water quality FAQs (undated; chlorine more noticeable after a main is replaced; covered jug in the fridge, used within 24 hours; read 29 October 2026).
- Which?, Best water filter jugs, tried and tested (page dated 20 August 2026; the best jugs improve taste by softening hard water; harmful contaminants not tested; we paraphrase only the introduction and headings available to us; read 29 October 2026).
- The Homebrew Forum UK, forum thread on using a filter jug for brewing water (one poster's account, seen 29 October 2026).
- WaterKit, Water Test Kit (20-in-1 strip, 30 to 60 second read, optional rapid coliform test read after 24 to 48 hours, strips from £3.99, free 2nd Class delivery on every order, 30-day money-back guarantee) and results portal. The three-strip method and the chart-step table are WaterKit's own reading of the colour chart.
Contains public sector information licensed under the Open Government Licence v3.0.