In stock · ships freeClarisink RO-400 Reverse Osmosis System
£199.00
VAT included · Free UK delivery · Typically arrives in 4–21 business days
- Shipped via UK Tracked Delivery
- 60-Minute Simple DIY Setup
- 2-Year Comprehensive Warranty
- Engineered for Hard UK Tap Water
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- Free UK delivery on every order, no minimum spend
- 2-year warranty on all filtration systems
- 30-day returns if it isn't right for your kitchen
- Fits a standard UK cold feed — no plumber required
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Best under sink water filter UK families can rely on
Finding the best under sink water filter uk families can rely on is essential if you want to eliminate cloudiness, chemical odours, and heavy limescale from your daily kitchen tap water.
About this product
The RO-400 is the middle of our three reverse osmosis systems and the one most UK kitchens end up with. Water passes through four stages in sequence: a sediment filter catches grit and rust from the mains, granular carbon takes out the chlorine taste, a dense carbon block picks up the finer organic compounds, and the RO membrane does the actual heavy lifting on dissolved solids.
That last stage is what separates reverse osmosis from a jug filter or a plumbed-in carbon filter. A carbon filter improves how water tastes. An RO membrane physically removes what is dissolved in it — which, on UK mains supply, means the calcium and magnesium behind kettle scale, plus any lead that older plumbing has contributed on the way to your tap.
Filtered water is stored in a pressurised tank so it is there when you want it rather than trickling through on demand. The trade-off is cupboard space: the tank is roughly the size of a football and lives alongside the filter bank.
Dispatched from our UK warehouse, with delivery in 4-21 business days depending on the item. That is slower than a next-day marketplace and we would rather say so up front than surprise you at the door.
Technical specifications
- Connection size
- Standard UK 15mm push-fit / compression
- Micron rating
- 0.0001 micron
- Lifespan
- 6 months or 4,000 litres (whichever comes first)
Litres and centimetres are used throughout. Cartridge life is measured in litres of filtered water, so heavily used households will change theirs sooner.
Specifications
| Filtration stages | 4 (sediment, granular carbon, carbon block, RO membrane) |
|---|---|
| Membrane rating | 0.0001 micron |
| Rated output | 400 GPD (approx. 1,500 litres per day) |
| Tap flow rate | approx. 1.5 litres per minute |
| Storage | Pressurised tank, approx. 3.2 gallons / 12 litres |
| Waste-water ratio | approx. 2:1 (2 litres to drain per litre filtered) |
| Pre-filter life | 6-12 months |
| Membrane life | 2-3 years |
| Power required | No — mains water pressure only |
| Under-sink footprint | approx. 42cm W x 42cm H x 20cm D, plus tank |
| Minimum mains pressure | 2.8 bar |
Figures marked with this symbol are provisional and are being confirmed against the manufacturer's datasheet. We publish them as estimates rather than leaving the row blank, and we do not claim any certification or test result we cannot evidence.
What this filter addresses
- Dissolved solids (TDS) — the minerals measured in hard-water readings
- Chlorine and chloramine used in UK mains treatment
- Fluoride added by some UK water authorities
- Heavy metals including lead picked up from older pipework
- Sediment and particulates
What it will not do
- RO sends water to the drain as part of how it works — expect roughly two litres wasted per litre filtered. If your household is metered, factor that into running cost.
- RO strips beneficial minerals such as calcium and magnesium along with the unwanted ones. Some people find the resulting water tastes flat. If that matters to you, the RO-500 adds a remineralisation stage.
- It filters one tap, not the whole house. Your shower, bath and washing machine still receive unfiltered mains water.
- It needs a drain connection and reasonable mains pressure. Low-pressure homes may need a booster pump.
Will this fit?
Check these before you order — they are the questions we are asked most often.
- Requires a 35mm sink or worktop hole for the dedicated filter tap (included)
- Needs a waste-pipe connection for the drain line
- Takes replacement cartridge AF-RO400M (membrane) and AF-CBC1 (carbon block)
Still not sure? Send us your sink and pipework details and we will confirm before you buy.
Not sure which RO system?
The RO-300, RO-400 and RO-500 differ on output, footprint, waste water and whether they need a power socket. Compare all three side by side before you commit.
Compare RO-300 vs RO-400 vs RO-500Customer reviews
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