“Water filter tap” covers two very different products, and shops happily blur them. A tap-mounted filter screws onto your existing spout and does the filtering itself. A 3-way filter tap (or triflow tap) is a full mixer with a third waterway for filtered water, and it filters nothing: it is the delivery end for an under-sink system.
This guide compares both honestly: the two tap-mounted filters we rate for a no-plumbing start, and the 3-way tap we recommend when an under-sink filter deserves a proper spout.
This guide contains affiliate links. If you buy through these links, we earn a small commission at no extra cost to you. This funds our independent water quality research. Our recommendations are based on real contaminant data, not sponsorship. Full disclosure
Quick picks
Best tap-mounted filter
TAPP Water EcoPro
Fits in minutes, total PFAS reduction claim, recyclable cartridges
£60
Budget tap-mounted
Waterdrop WD-FC-06 Tap Filter
Chlorine, lead, and fluoride reduction for £30
£30
Best 3-way filter tap
Osmio Sofia Long Reach 3-Way Triflow Tap
Hot, cold, and filtered from one spout; pair with an under-sink filter
£207
Which type of filter tap do you need?
Tap-mounted filter: the no-plumbing start
Screws onto a standard round spout in minutes, no tools, no plumber, and moves out with you, which makes it the renter's option. The cartridge does real work on chlorine and lead, but it is small, so expect to replace it every few months and accept a slower filtered-water flow than the open tap.
3-way filter tap: the finished under-sink setup
A triflow tap replaces your kitchen mixer and adds a third, separate waterway fed by whatever filter lives in the cupboard below. The tap removes nothing by itself, so it only makes sense together with an under sink water filter or a reverse osmosis system. What it buys you is one clean spout instead of a second drilled hole in the worktop.
Neither fixes hardness
No filter tap reduces limescale. If scale is the problem you are trying to solve, check your water hardness by postcode first; hard water areas need a softener, not a tap filter.
First, check what is in your water
Enter your postcode to see the contaminants measured in your area, so you pick the filter your water actually needs.
Try your postcode — e.g. SW1A, M1, B1
The filter taps we rate
Best 3-way tap — pair with an under-sink filter
Osmio Sofia Long Reach 3-Way Triflow Tap
Filter Tap
Why it fits
Separate spout keeps filtered water from mixing with the hot and cold supply
Hot, cold and filtered from one fitting, so no second spout on the worktop
Made in Italy, with a 3-year warranty on parts and valves
Trade-offs
Filters nothing by itself: you still need an under-sink or RO system behind it, from about £60 extra
Osmio recommend a pressurised hot water system; on gravity-fed hot water the flow may be too low unless it is pumped
Affiliate link: we may earn a commission at no extra cost to you.
TAPP Water EcoPro — Best tap-mounted filter
TAPP Water EcoPro
£60
The most capable filter that fits without opening a single cupboard.
The EcoPro is the tap-mounted filter we point people to first. It clips onto a standard spout in a couple of minutes and its carbon block covers the everyday list, chlorine, lead, and microplastics, with a total PFAS reduction claim published by TAPP on top. The cartridges are recyclable through TAPP's return scheme, which answers the usual objection to disposable tap filters. Honest limits: the PFAS figure is the manufacturer's own testing rather than an NSF verification, the filtered flow is noticeably slower than the open tap, and it will not fit pull-out sprayers or most designer taps, so check your spout before ordering.
Removes
ChlorineLeadMicroplasticsPFAS (total)
SGS tested
Pros
Removes microplastics and PFAS — rare for a tap filter
Biodegradable filter cartridges reduce waste
Subscription model means filters arrive on time
Cons
–SGS tested rather than NSF certified
–Higher upfront cost than basic tap filters
–Requires specific tap adapter — check compatibility first
At £30 the WD-FC-06 exists for one job: make the water from your existing tap taste better without any commitment. The carbon cartridge reduces chlorine, lead, and fluoride, which is an unusual claim at this price, and swapping cartridges takes seconds. The trade-offs are what you would expect at the entry point: shorter cartridge life than the EcoPro, no PFAS claim at all, and the same standard-spout limitation every tap-mounted filter shares. If it fits your tap and your budget, it is a fine first step; if you find yourself refilling glasses all day, that is the sign to move under the sink.
Removes
ChlorineLeadFluoride
NSF/ANSI 42
Pros
Clips onto most standard UK taps in minutes
Switch between filtered and unfiltered flow
Compact design that doesn't dominate the counter
Cons
–Not compatible with pull-out or spray taps
–Limited contaminant removal compared to under-sink
The clean way to finish an under-sink filter installation.
The Sofia is a full kitchen mixer with a third, separate waterway for filtered water, in a brushed finish that does not announce itself as water-treatment kit. Be clear about what you are buying: the tap itself filters nothing, which is exactly why it appears here with an empty removals list. Its job is to give the filter under your sink a proper spout, so you get hot, cold, and filtered from one fitting instead of drilling the worktop for a separate mini tap. Build quality is solid, the long-reach spout suits double sinks, and the filtered waterway keeps treated water out of the brass mixer body. Budget for the filter itself separately, and for an hour or two of fitting if you have not swapped a kitchen tap before.
Pros
Separate spout keeps filtered water from mixing with the hot and cold supply
Hot, cold and filtered from one fitting, so no second spout on the worktop
Made in Italy, with a 3-year warranty on parts and valves
Cons
–Filters nothing by itself: you still need an under-sink or RO system behind it, from about £60 extra
–Osmio recommend a pressurised hot water system; on gravity-fed hot water the flow may be too low unless it is pumped
–Rated 97/100 by Osmio, but on only 4 reviews, and the finish is warranted for 1 year against 3 on the valves
Cartridge costs are the manufacturer’s stated replacement schedule at typical UK household use. Yours will vary with how much water you filter and how hard it is. Prices are approximate — the retailer sets the final price. Across this table the gap between cheapest and dearest to own is £190.
Renting, or just testing the water? The TAPP Water EcoPro is the tap-mounted filter to get, with the Waterdrop WD-FC-06 as the £30 fallback when budget decides.
Committed to filtered water every day? Put the money under the sink and finish the job with the Osmio Sofia triflow tap: one spout, three waterways, no second hole in the worktop.
A 3 way tap (also sold as a triflow tap) replaces your kitchen mixer and dispenses hot, cold, and filtered water from one spout, each through its own internal waterway. The tap itself contains no filter: it is the delivery end for an under-sink filter or reverse osmosis system hidden in the cupboard below. You buy it to avoid drilling a second hole in the worktop for a separate filtered-water tap.
Do tap-mounted water filters actually work?
Within their limits, yes. A tap-mounted filter like the TAPP Water EcoPro or Waterdrop WD-FC-06 screws onto the spout in minutes and its carbon block genuinely reduces chlorine, lead, and in the EcoPro's case carries a total PFAS reduction claim. The limits are real too: small cartridges mean more frequent replacement, flow through the filter is slower than the open tap, and they fit standard round spouts only, so pull-out sprayers and some designer taps are out.
Should I get a filter tap or an under sink filter?
They answer different budgets rather than different jobs. A tap-mounted filter costs £30 to £60 and needs no tools, which makes it the right first step for renters or anyone testing whether filtered water is worth it to them. An under sink filter with its own tap or a 3 way tap costs more up front but runs cheaper per litre, filters at full mains pressure, and keeps the spout clear. If you already know you filter every glass, start under the sink.
Can I fit a 3-way tap myself?
If you are comfortable swapping a kitchen tap, a 3-way tap is the same job plus one extra flexible hose to the filter: isolate the water, disconnect the old mixer, seat the new tap, and connect hot, cold, and the filter line. Allow an hour or two. If the existing tap has seized fittings or your sink has no isolation valves, a plumber will charge roughly £80 to £150 for the swap.
