Best under-sink water filters UK 2025 — high-capacity filtration, dedicated tap, what they remove, installation, and top products. Enter your postcode to see which filter is right for your water.
Free · Instant · No sign-up
This page contains affiliate links. We may earn a small commission if you purchase — at no extra cost to you. All products are independently reviewed.
Under-sink water filters provide high-capacity, on-demand filtered water at the kitchen tap. Unlike jug filters that require manual filling and have limited capacity, under-sink systems connect directly to the cold water supply and produce filtered water continuously. Most systems install beneath the kitchen sink and feed a separate dedicated tap (typically a small chrome lever tap installed next to the main tap), though some models attach directly to the existing tap.
Under-sink systems range from simple single-stage activated carbon filters that reduce chlorine and taste, through multi-stage carbon block systems that add sediment filtration and heavy metal reduction, to full reverse osmosis (RO) systems that remove virtually all contaminants including PFAS. The right choice depends entirely on what's in your water — enter your postcode above to check your zone's data.
Single or dual-stage carbon filters (£50–£100) are the entry level. A sediment pre-filter catches particles; a carbon block filter removes chlorine, taste, and some heavy metals. Good for improving tap water taste in areas without major contaminant concerns. Multi-stage carbon systems (£100–£200) add additional filter stages — typically a second carbon block — for better chlorine, heavy metal, and taste reduction. Some include NSF/ANSI 53 certification for lead reduction. Under-sink RO systems (£200–£400) are the most comprehensive option. An RO membrane followed by a post-carbon polisher removes 99%+ of all contaminants including PFAS, nitrates, arsenic, and microplastics. NSF/ANSI 58 certified systems are the only proven option for PFAS removal.
Most under-sink carbon filter systems can be installed by a confident DIYer — the connection is typically via push-fit fittings to the cold water supply pipe under the sink. A small hole must be drilled in the sink or worktop for the dedicated filter tap (if not using a tap-attachment model). An RO system additionally requires a drain connection for the reject water. Professional installation by a plumber costs £50–£100 and is worth considering if you are not confident with plumbing. All systems should use WaterSafe-approved installers where professional installation is used.
Under-sink filter cartridges typically need replacing every 6–12 months depending on usage and water quality. Annual filter costs range from £30–£80 for carbon systems and £60–£150 for RO systems (multiple stages). The RO membrane itself usually lasts 2–3 years. On a per-litre basis, under-sink filters typically cost £0.01–£0.05/litre — cheaper than bottled water (£0.50–£2/litre) and far better for the environment.
A under sink filters removes: Chlorine and chloramine, Taste and odour, Some heavy metals (in certified models). It does NOT remove: PFAS (unless RO system), Nitrates (unless RO).
Whether you need a under sink filters depends on your water quality. Enter your postcode above to check your zone's parameters and see what your water contains.
See the product comparison above for current pricing. Costs vary from £119 to £44 depending on type and features.
Only reverse osmosis (RO) filters certified to NSF/ANSI 58 remove PFAS from tap water. Standard carbon filters, jug filters, and water softeners do NOT remove PFAS.
Filter cartridges in under sink filters systems typically need replacing every 6–12 months. Check the manufacturer's specification for your specific model.