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Countertop water filters: compare UK models and costs
Keep filtered water within reach without fitting a system under the sink. Compare a tap-fed ceramic filter with a refillable reverse osmosis unit, including UK prices, replacement costs and the space each needs.
Photo: Doulton
Compare countertop filters
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These two systems suit different kitchens: Doulton uses your tap’s water pressure; Waterdrop needs a socket and a tank you refill. This comparison uses manufacturer specifications. We have not tested these products.
Photo: Doulton
Doulton countertop system with Biotect Ultra
Tap-fed ceramic filter · D-CS / D-CP Biotect Ultra
The plastic finish is listed from £184.95 in Doulton’s collection; we have read only the chrome product page, so the lower figure is not a chrome price.
A small ceramic-filter unit that diverts your existing cold tap through the cartridge, so there is no second tap to fit.
See the countertop system at Doulton Affiliate link
In the box: M22 diverter and a Biotect Ultra 2501 filter[1].
- Connects to
- Your existing cold tap. It needs a compatible thread or a removable aerator, and it will not suit every pull-out spray tap.[1]
- Water
- Cold water only, up to 30 °C, at 10 to 125 psi.[3]
- Filter
- Biotect Ultra 2501 at £29.45, rated 2,300 litres, replaced every 6 months.[3][4]
- Before first use
- Run it for 10 minutes, leave it for 24 hours, then run it for 10 minutes again.[3]
- Spares
- Takes the 2501 and 2505 SI only: not the DUO pre-filters, gravity elements or Ultracarb.[1]
Think twice if you have a pull-out spray tap or a tap with no removable aerator, or want hot water filtered.
Photo: Waterdrop
Waterdrop C1SL countertop reverse osmosis system
Plug-in reverse osmosis · C1SL
£229.00[5]
The normal public price; a lower member price is shown on the page and is left out here. The crossed-through £259 is not a price we compare.
An electric countertop reverse osmosis unit with a refill tank and a detachable pitcher. It needs no tap connection and no drilling, and it produces drain water as well as purified water.
In the box: The C1RFG filter (not the C1RF)[5].
- Connects to
- Nothing: you fill the tank by hand and plug the unit in. It needs no tap connection or drilling.[5]
- Size
- 29.7 × 21.1 × 34.8 cm, so check the space under the wall units.[5]
- Wastewater
- The maker states a ratio of 3 parts purified water to 1 part drain water. That is the maker’s claim, not our test.[5]
- Filter
- The C1RFG is £69.00, not the C1RF. The maker says 12 months or 1,100 US gallons. The system’s product card showed it as sold out and its own page is unclear about stock, so check before you buy.[5][6]
- What we did not check
- The instruction manual Waterdrop links is for the WD-C1S family, so we found no manual for the C1SL itself. We quote no performance, certification or health claim for it.[5]
Think twice if you want the lowest running cost: the filter is £69.00, or are short of worktop or wall-unit space, or cannot get the replacement filter when you need it.
Side by side
| Product | How it works | Price | Connects to | Fitting and power | Filter and change |
|---|---|---|---|---|---|
| Doulton countertop system with Biotect Ultra | Ceramic filter on a diverter at your tap[1] | £234.95 chrome; plastic from £184.95[1][2] | Your existing cold tap, if the thread or aerator allows[1] | Fits onto your tap with the M22 diverter; follow Doulton’s instructions[1][3] | 2501 at £29.45, every 6 months[3][4] |
| Waterdrop C1SL countertop reverse osmosis system | Electric reverse osmosis with a refill tank[5] | £229.00[5] | Nothing: filled by hand[5] | Plug-in; no tap connection or drilling; makes drain water[5] | C1RFG at £69.00; maker says 12 months or 1,100 US gallons; stock unclear[5][6] |
Prices are the sellers’ displayed UK prices on 16 October 2026, before delivery, and change. For fit and plumbing, the countertop guide explains the types and the space they need.
Three kinds of countertop filter
“Countertop” covers filters that work very differently. The first thing to settle is how you want the water to reach the filter.
A tap-fed ceramic filter takes cold tap water through a diverter and a ceramic filter into your glass. A gravity filter is filled by hand into an upper chamber, passes through filter elements into a lower chamber, and is dispensed by spigot or by pouring. A plug-in reverse osmosis unit is filled by hand into a tank, passes through a pump and membrane into a pitcher, and also produces drain water.
- Your tap can take a fittingA ceramic filter that attaches to the tap. It needs a compatible thread or a removable aerator, and cold water only.
- You don’t want anything on the tapA gravity filter, which you fill by hand and which needs no tap connection, electricity or plumbing.
- You want reverse osmosis without plumbingA plug-in unit with a refill tank. It makes drain water as well, so read the reverse osmosis guide first.
- You can fit something under the sinkCompare the under-sink systems; they leave the worktop clear.
How to choose
- Look at your tap first. A ceramic filter on the tap needs a compatible thread or a removable aerator, and will not suit every pull-out spray tap. If yours cannot take it, a gravity filter or a plug-in unit is the way round.
- Measure the space. The plug-in reverse osmosis unit is 29.7 × 21.1 × 34.8 cm and needs a socket. A gravity filter is taller: the 6 litre Doulton is 473 mm.
- Add up the filters. The ceramic filter’s cartridge is £29.45 every six months. The reverse osmosis filter is £69.00 on the maker’s 12-month figure, and it was shown as sold out. The running-cost calculator adds either to the purchase price over one, three and five years.
- Match filtration to your goal. Taste, limescale and a specific contaminant call for different checks. For a removal claim, look for a test report or certification covering the exact model and cartridge; a brand-wide claim is not enough.
Common questions
Does a countertop water filter need plumbing?
It depends on the kind. The Doulton unit attaches to a tap you already have, so it needs the right thread or a removable aerator and can often be fitted yourself if the tap is compatible. Follow the instructions and get fitting help if needed. The plug-in reverse osmosis unit and gravity filters need no tap connection and no drilling.
Can a countertop filter use hot water?
Doulton’s instructions say cold water only, up to 30 °C. Check the instructions for any unit you buy.
How often does a countertop filter need changing?
It depends on the model. Doulton’s Biotect Ultra 2501 is rated 2,300 litres and replaced every six months. Waterdrop says its C1RFG lasts 12 months or 1,100 US gallons. See how the time or litre limit decides.
Is a countertop filter the same as a jug?
No. A jug is filled and poured; the systems here connect to a tap, are filled into a tank, or work from an upper chamber. See the countertop guide for how the types differ, and whether a filter is worth it at all.
Related guides
- Countertop water filters: types, space and upkeep explains the kinds in general.
- Gravity water filters compares two systems that need no plumbing or power.
- Under-sink water filters compared for a system out of sight.
- Replacement cartridges and the care guide for keeping a system running.
Sources
- Doulton: countertop system with Biotect Ultra read 16 October 2026
- Doulton: filter systems collection read 16 October 2026
- Doulton: countertop filter instructions (PDF) read 16 October 2026
- Doulton: Biotect Ultra 2501 cartridge read 16 October 2026
- Waterdrop: C1SL countertop reverse osmosis system read 16 October 2026
- Waterdrop: C1RFG replacement filter read 16 October 2026
Read on 16 October 2026 from the makers’ own pages. How we check.