How to choose a water filter
Dozens of filter types, confusing jargon, and every brand claiming to be the best. Answer 3 quick questions below and get matched with the right system — or read the full guide underneath the tool.
Find your water filter
The 3 questions that actually matter
Before comparing brands or features, answer these honestly. They determine almost everything about which filter is right for you.
What is actually bothering you?
Bad taste and chlorine smell need a different filter to limescale, and both need a different filter to lead or PFAS removal. These are not the same problem and not the same solution.
Drinking water only, or the whole property?
A kitchen tap filter only treats what you drink and cook with. A whole house system treats every tap, shower and appliance. Most UK homes only need the kitchen tap covered for drinking water.
Do you own the property or rent it?
Renters generally cannot make permanent plumbing changes. Countertop and faucet filters need zero drilling. Under-sink systems need a small, reversible modification most landlords approve.
Water filter types explained simply
Not every filter does the same job. Here is what each type actually removes — and what it does not.
Carbon filter
Removes chlorine, odour and improves taste. The most common and affordable type. Does not remove limescale, lead or PFAS reliably.
Reverse osmosis (RO)
Removes 99%+ of lead, fluoride, PFAS, chloramine and dissolved minerals. The most thorough filtration available for drinking water. Drops London TDS from 320ppm to ~12ppm.
Water softener
Removes calcium and magnesium using ion exchange — eliminates limescale completely. Does not purify drinking water. Pair with an RO system at the kitchen tap for full protection.
Under sink filter
Hidden under the kitchen sink with a dedicated tap. Carbon or RO options available. Good balance of performance, space and cost. Starts from £180 installed.
Whole house filter
Fitted at the mains entry point. Treats every tap, shower and appliance. Reduces chlorine and sediment throughout the property. Best paired with a softener for limescale too.
Salt-free conditioner
Prevents scale from forming without removing hardness minerals or using salt. Lower maintenance than a softener but less effective on very hard water like London's 320ppm supply.
Match your concern to the right filter
Already know what you want to fix? This table gives you the direct answer.
| Your concern | Right filter | Price from | What it does not fix |
|---|---|---|---|
| Bad taste, chlorine smell | Carbon or RO under sink | £180 | Limescale, hardness |
| Lead or PFAS concern | Reverse osmosis | £649 | Whole-property limescale |
| Limescale everywhere | Water softener | £800 | Drinking water purity |
| Dry skin or hair | Water softener | £800 | Drinking water taste |
| Renting, no drilling | Countertop or faucet filter | £80 | Whole-property coverage |
| Protect boiler & appliances | Whole house filter or softener | £650 | Point-of-use purity |
| Instant hot water | Waterdrop K6 Hot RO Tap | £1,190 | Whole-property limescale |
| Complete home protection | Softener + RO at kitchen tap | £1,449 | Nothing — full coverage |
All prices include professional installation by our own engineers. Book a free water test if you are unsure which concern applies to your home.
Does London water need a filter?
London tap water is legally safe — Thames Water meets UK Drinking Water Inspectorate (DWI) standards. But safe and clean are not the same thing. London tap water averages 320ppm TDS, the hardest in the UK, driven by chalk and limestone geology in the Thames catchment.
Thames Water uses chloramine for disinfection — it is more stable than plain chlorine but leaves a stronger chemical taste and smell. Properties built before 1970 commonly have lead service pipes, and a 2026 Imperial College London study detected PFAS "forever chemicals" in tap water samples across 28 London boroughs.
A filter is not legally required. But for taste, lead and PFAS — which affect most London properties — a reverse osmosis system addresses all three at once. A water softener is needed separately for limescale.
Common mistakes when choosing a water filter
Assuming one filter does everything. A carbon jug filter will not touch limescale. A water softener will not remove lead. Match the filter to the specific problem, not the other way round.
Ignoring running costs. A cheaper system with frequent filter changes can cost more over three years than a pricier one with longer-lasting cartridges. Always check annual replacement cost before buying.
Skipping a water test. If you are not sure what is in your water — hardness level, chlorine, lead risk from older pipework — a quick test removes the guesswork. We test your water before and after every installation and hand you a written report.
Not checking water pressure. RO systems need between 15 and 85 psi to work correctly. London flats often have lower mains pressure than houses. We check this before every installation and fit a booster pump if needed at no extra charge.
Frequently asked questions
Start with what you want to fix. For better-tasting drinking water and chlorine removal, a carbon filter or reverse osmosis system at the kitchen tap works well. For limescale and hard water across the whole property, you need a water softener. For lead, PFAS or fluoride, reverse osmosis is the only filter type that removes these reliably. Renters should look at countertop or faucet filters that need no drilling.
A water filter removes contaminants like chlorine, sediment, lead and PFAS, improving taste and safety. A water softener removes calcium and magnesium, the minerals that cause limescale and hard water. Filters do not soften water, and softeners do not purify drinking water. Many London homes use both together for complete protection.
Standard carbon filters do not remove limescale. Reverse osmosis systems remove the dissolved calcium and magnesium from drinking water specifically, dropping TDS from 320ppm to around 12ppm in London — but this does not affect the rest of your home's water supply. To stop limescale on your boiler, shower and washing machine, you need a dedicated water softener or whole house system.
Yes. Countertop and faucet-mount filters need no plumbing changes and come with you when you move. Under-sink filters require one small, reversible modification — a hole for a dedicated tap — that most landlords approve. We have installed filters in hundreds of London rental properties across all boroughs.
A carbon filter improves taste and removes chlorine, which is enough for many households. If lead, PFAS or fluoride are a concern — especially in pre-1970 London properties — reverse osmosis is the only home filtration method that removes these reliably, typically dropping TDS to around 12ppm.
Under-sink carbon filters start from £180 installed. Reverse osmosis systems (Waterdrop G2P600) are £649 installed. Whole house filters start from £650 and water softeners from £800. All prices include supply, professional installation by our own engineers, and a written TDS water test report.
Still not sure which filter you need?
Use the tool above to get matched in 30 seconds, or talk to us directly — we will test your London water and recommend the right system, no upselling, same week.
