If your priority is filtered water you may have come across systems that you install under your kitchen sink, filtering your tap water.
You might pay £50 for a simple cartridge system that goes between the water pipe and your kitchen tap (you’ll need to replace every 6-months or so). Prices rise to £1,000+ for more complex systems. Unless you’re handy at DIY, you’ll need a plumber to install a basic system, and you’re unlikely to want to attempt to install the more complex systems! You’ll likely need a plumber for maintenance too.
Needless to say, you only get water-filtering – no instant hot water and delicious chilled water for you!
Instant hot water
Instant chilled water
Doesn't take up cupboard space