Filter taps
A dedicated tap for filtered water, or a three-way tap combining hot, cold and filtered in a single spout.
If you fit an under-sink filter you need somewhere for the filtered water to come out. There are two approaches and the choice is more consequential than it looks, because one of them involves drilling your worktop.
A separate filter tap is a small dedicated spout beside the main tap. It needs its own hole. The advantage is that filtered water stays entirely separate from the main supply, and the filter only treats what you actually drink.
A three-way tap replaces your existing mixer and delivers hot, cold and filtered through one spout, with a separate lever or handle for the filtered line. No extra hole, and it looks tidier. The trade-off is that you are replacing a working tap, and the filtered channel runs through the same spout as unfiltered water — which most people are entirely relaxed about, but it is worth knowing.
Best for
- Any under-sink or RO installation
- Kitchens where a second hole is unwelcome — go three-way
- Replacing a tired mixer tap and adding filtration at once
- Keeping the filtered line entirely separate — go separate tap
Common on office drinking water points.
Pros and cons
Pros
- Filtered water on demand with no jug and no waiting
- Three-way taps avoid drilling entirely
- Wide choice of finishes to match existing fittings
- A separate tap keeps the filtered line isolated
Cons
- A separate tap means a permanent hole in the worktop
- Three-way taps cost noticeably more than a plain mixer
- Stone and composite worktops need professional drilling
- Not a landlord-friendly modification without permission
Can you install it yourself?
Get a plumber for this one
Skill level: Moderate to Advanced · Time: about 2 hours
The plumbing is easy. The hole is not, and it is the part that cannot be undone. A cracked quartz worktop costs many times what the plumber would have. On laminate this is DIY; on stone, it is not.
Tools you will need
- Drill
- Hole cutter appropriate to the worktop material
- Basin wrench
- Adjustable spanner
- Silicone sealant
Call a plumber if
- The worktop is granite, quartz, composite or solid surface
- You are replacing an existing mixer with a three-way
- There is no existing spare hole
Maintenance
Nothing routine. Descale the aerator occasionally in a hard water area.
What installation costs
£120–£350 indicative UK labour
Labour only. Drilling a stone or composite worktop is the variable, and some plumbers subcontract it.
