Most people have noticed this at some point. A cup of tea made with the usual brand tastes oddly flat in a holiday cottage. A coffee from a café two towns over has a softness the same beans never quite reach at home. The leaves haven’t changed, the kettle works fine, and yet the cup in hand isn’t the cup expected. More often than not, the variable nobody thinks to question is the water.
Most of what’s in your cup is water
It’s easy to treat water as the neutral background to a drink, rather than part of it. In practice, a cup of black coffee is somewhere around 98% water, and tea isn’t far behind. Whatever character that water carries ends up making a fair share of the flavour, sitting alongside the beans or leaves rather than remaining in the background. Anything dissolved in it, for better or worse, comes along for the ride.
That’s why the same brand of tea or coffee can taste subtly different depending on where the kettle is filled. The tea is doing its job. The water underneath it is telling a slightly different story each time.
What’s actually coming out of the tap
UK tap water is safe to drink, well regulated and varies a good deal by region. The differences that matter to flavour mostly come down to two things: dissolved minerals and the chemicals used in treatment.
Calcium and magnesium are the main minerals, and the quantity contained in water determines whether an area has hard or soft water. Cardiff and much of South Wales sit on the softer end, while large parts of southern and eastern England are noticeably harder. Chlorine – used to keep supplies safe on their journey to the tap – is the other common influence. Even small traces can leave a faint swimming-pool note that’s easier to detect in something delicate like green tea, as opposed to in a strong builder’s brew.
It’s worth being clear that this is about taste and aroma – not health. Hard water isn’t bad for anyone; it just behaves differently in a cup.
The hard water question
Higher mineral content tends to mute the brighter, more aromatic notes in coffee and tea, which is partly why a brew in a hard-water area can taste rounder yet duller than the same drink brewed with softer water. It’s also the reason why kettles in those regions become coated in limescale so quickly. If you’re seeking to soften that effect, reduce the chlorine taste or cut down on scale, take a look into home water filtration, which ranges from simple jug filters to under-sink system, depending on how far you want to take it.
None of this means a filter is essential, however. In fact, plenty of people are perfectly happy with their tap water as it is. But for anyone who’s curious about why their morning cup never quite matches the café version, the water is a sensible place to start looking.
Temperature and freshness still count
Water chemistry isn’t all there is to it, either. Freshly drawn water holds more dissolved oxygen, which is why tea made from a kettle boiled and reboiled three times can taste lifeless. Temperature matters, too: black tea and coffee can handle water just off the boil, while green and white teas prefer it a little cooler – closer to 80°C – so the leaves don’t scald. These are small habits, but they’re often what separates a good cup of tea or coffee from a forgettable one.
A few things worth trying
The most honest way to find out whether water is affecting a brew is to taste it side by side. Make two cups the same way, one with tap water and one with filtered or bottled, and compare them properly. The gap is sometimes obvious and sometimes barely there, which is useful to know either way before spending money on anything.
Beyond that, a few easy habits help: fill the kettle with fresh water each time rather than reboiling, descale it regularly if limescale builds up quickly, and let just-boiled water rest for a moment before pouring it over more delicate teas. None of it is complicated, and the cup tends to thank you for it.
Have you noticed a difference in the taste of tea or coffee when travelling or moving house? Share your experiences in the comments below.