The Best Water for Coffee: Tap, Filtered or Bottled?

The best water for coffee is clean, fresh and moderately hard: it should taste good on its own, with no chlorine smell, and contain some minerals but not too many. For most people in the UK, filtered tap water is the simplest way to get there.

Water makes up around 98% of a cup of filter coffee, so it has a bigger effect on the taste than most people realise. The same beans can taste bright and sweet with one water and flat or bitter with another.

Why minerals matter

The minerals in water, mainly calcium and magnesium, help pull flavour out of the coffee. Water with too few minerals (very soft or distilled water) gives a flat, sour, under-extracted cup. Water with too many (very hard water) can taste chalky and dull, and it leaves limescale in kettles and machines.

The Speciality Coffee Association's guidance is for water with a moderate mineral content, a neutral pH and no chlorine or odours. You don't need to measure all that at home: if your water tastes clean and fresh, you're most of the way there.

Hard or soft water?

Water hardness varies a lot around the UK. Much of the south and east of England has hard water, while Scotland, Wales and the north-west tend to have soft water. Your water company's website will tell you how hard your water is.

• Hard water: a jug filter reduces the minerals and chlorine, improves the taste and cuts down on limescale. Descale your kettle and machine regularly.
• Soft water: usually great for filter coffee. If your coffee tastes thin or sour, try a bottled spring water with a little more calcium and magnesium.

Tap, filtered or bottled?

• Filtered tap water is the best everyday choice for most people. A jug filter removes chlorine and some hardness.
• Bottled water can work well, but brands vary a lot. Choose a still spring water with a moderate mineral content and check the label.
• Distilled or reverse-osmosis water on its own is too pure and makes flat, sour coffee. Avoid it unless you add minerals back.

Try a taste test

The easiest way to find out what works for you is to brew the same coffee with two or three different waters side by side. You may be surprised how different they taste. Then make sure the rest of your brew is right too, with our tips on making better coffee at home and how much ground coffee to use.