Does water quality affect coffee and tea?

Water is the largest ingredient by a wide margin, and its mineral content directly affects extraction. This is why the same beans taste noticeably different in a hard water area than a soft one, using identical equipment.

What you'll need

• A filter jug or plumbed filter (optional)
• Bottled water for comparison (optional)

Step by step

1. Find out whether your water is hard or soft.Your water company publishes it. Limescale in the kettle is the obvious sign of hard water, and it affects both taste and equipment.
2. Understand what minerals do.Some mineral content helps extract flavour compounds. Too much — particularly bicarbonate — mutes acidity and makes coffee taste flat and chalky.
3. Do not use distilled or deionised water.Water with no mineral content extracts poorly and tastes hollow. It is a common misconception that purer is better here.
4. Use a filter jug in a hard water area.It reduces hardness and removes chlorine. It is the simplest meaningful improvement and it also protects the kettle and machine from scale.
5. Let chlorinated water stand, or filter it.Chlorine is detectable in tea especially. A carbon filter removes it, and standing water uncovered for a few hours reduces it.
6. Descale equipment regularly in hard water.Scale on heating elements affects temperature stability and eventually causes failure. It also gives a flat, slightly metallic taste.
7. Try bottled water as a comparison.Brew the same coffee with your tap water and with a low-mineral bottled water. It tells you quickly whether water is your limiting factor.
8. Note that tea is more sensitive than coffee.Hard water noticeably dulls tea and causes the film on the surface. Green and delicate teas suffer most.

Tips

• The scum on the surface of tea in hard water areas is a reaction between minerals and tea compounds. Filtered water largely eliminates it.
• Filter cartridges need replacing on schedule. An exhausted filter does nothing and can make water worse.
• If you have a water softener, note that softened water is often unsuitable for brewing — it exchanges hardness minerals for sodium rather than removing them.

Common mistakes

• Using distilled or heavily purified water — Some mineral content is needed to extract flavour properly. Water with none gives a flat, hollow cup.
• Ignoring water in a hard water area — It mutes flavour, scales equipment and affects tea particularly. Filtering is inexpensive and makes a noticeable difference.
• Never replacing a filter cartridge — An exhausted filter stops working and can harbour bacteria. Replace on the stated schedule.

Questions people ask