What in the water affects taste
- Minerals (hardness): calcium and magnesium help pull flavor out of the coffee. Water with none tastes flat.
- Alkalinity (buffer): bicarbonate neutralises acidity. Too much makes coffee dull and chalky; too little makes it sharp.
- Chlorine and odors: these carry straight into the cup.
The target
The Specialty Coffee Association gives a reference for brewing water. In round numbers:
| Measure | Target | Acceptable range |
|---|---|---|
| Total dissolved solids | 150 mg/L | 75–250 mg/L |
| Total hardness | About 68 mg/L | 50–175 mg/L |
| Alkalinity | About 40 mg/L | Near 40 mg/L |
| pH | 7 | 6.5–7.5 |
| Chlorine | 0 mg/L | None |
What to use at home
- Taste your tap water. If it smells of chlorine, use a carbon filter jug.
- If your water is very hard (limescale on the kettle is a sign), blend filtered tap water with low-mineral bottled water.
- If your water is very soft, or you use reverse osmosis, add minerals designed for brewing, or mix in some regular bottled water.
- Avoid distilled water. It has no minerals, so it makes flat coffee.
Bottled water labels list the mineral content, so you can look for total dissolved solids in the 75–250 mg/L range. Check your machine's manual too, since hard water builds scale inside brewers.
Try a side-by-side test
Brew the same coffee with your tap water and with filtered water, using the same pour-over recipe. If you notice a difference, you have found an easy upgrade.
How to test your water
An inexpensive TDS meter gives you a quick reading of dissolved minerals, and test strips can show hardness. Your local water supplier may also publish a report of your tap water. If your reading is far from the range above, try a filter or a different water, and compare the taste.
Keep your equipment clean
Hard water leaves limescale in kettles and machines. Descale regularly, following the manufacturer's instructions, so your equipment heats evenly and your coffee tastes clean.
Common questions
Is bottled water better than tap water?
Not always. A bottled water with moderate minerals can work well, but good filtered tap water is cheaper and often just as good.
Does boiling water remove chlorine?
Boiling helps remove some free chlorine, but not all chemicals, such as chloramine. A carbon filter is more effective.
Can I use softened water?
A water softener swaps calcium and magnesium for sodium, which reduces the minerals that help extraction. Many people prefer to filter drinking water separately for coffee.
