Brewing guide
Scottish water and your coffee
Coffee is mostly water, so what comes out of your tap shapes how your cup tastes. Most of Scotland has soft water. Here's what that means for your coffee, and a few simple tweaks to get the best from it.
The water in Scotland
Why most Scottish water is soft
The Drinking Water Quality Regulator for Scotland says most drinking water in Scotland is classified as soft. Most of it comes from lochs, rivers and burns, and the rocks that make water hard, like chalk and limestone, aren't common here. Some areas supplied from boreholes have harder water, so it's worth checking yours.
Water hardness is a measure of the calcium and magnesium dissolved in it. Scottish Water groups it into six bands, measured in milligrams per litre (mg/l).
Scottish Water hardness bands
- Soft: under 50 mg/l
- Moderately soft: 50 to 100 mg/l
- Slightly hard: 100 to 150 mg/l
- Moderately hard: 150 to 200 mg/l
- Hard: 200 to 300 mg/l
- Very hard: over 300 mg/l
In your cup
What soft water does to coffee
The minerals in water do two jobs when you brew. Calcium and magnesium help pull flavour out of the coffee grounds, and bicarbonate (the water's alkalinity) softens acidity.
Soft water has less of both. The Specialty Coffee Association notes that water with very low hardness tends to under-extract, and that low alkalinity makes coffee taste more acidic. So with soft water, you may find your coffee tastes brighter and lighter, and sometimes a little sour, especially as espresso.
What you might notice with soft water
- Bright, clear filter coffee
- More noticeable acidity
- Espresso that can taste sharp or sour
- Less limescale in your kettle and machine
Brewing tips
How to brew great coffee with soft water
These are starting points, not rules. Every grinder, kettle and machine is a little different, so change one thing at a time and taste as you go.
Not sure how fine to go? Our grind size guide shows the right starting point for each brew method, and every coffee page has our starting recipes for espresso and filter.
Simple tweaks for soft water
- Grind a little finer to extract more flavour
- Use water just off the boil for filter coffee
- Let cafetière and AeroPress brews steep a little longer
- Espresso tasting sour? Grind finer or pull a slightly longer shot
- Don't brew with distilled or reverse osmosis water on its own: with almost no minerals, coffee tastes flat
- If your tap water tastes of chlorine, a jug filter can help, but some also strip out minerals, so taste with and without
Check your water
Is your water hard or soft?
Scottish Water publishes water quality results for every area. Enter your postcode on Scottish Water's water quality page to see the hardness of your water, or call their Customer Helpline on 0800 0778 778.
Live elsewhere in the UK? Try our water and coffee postcode checker.
Looking after your kettle and machine
Soft water leaves less limescale, so kettles and coffee machines usually need descaling less often than in hard-water areas. Always follow your machine manufacturer's advice on water filters and descaling.
Scottish water and coffee questions
Is Scottish water good for coffee?
Yes. Most Scottish tap water is soft, which makes a clean, bright cup and leaves less scale in your kettle. You may need to grind a little finer, or brew a little longer, to get the most sweetness from your coffee.
How do I find out if my water is hard or soft?
Enter your postcode on Scottish Water's water quality page, or call their Customer Helpline on 0800 0778 778.
Should I use bottled water for coffee?
You don't need to. Tap water works well for most people. Avoid distilled or reverse osmosis water on its own, as coffee brewed with almost no minerals tastes flat. If you want to experiment, brew the same coffee with tap water and a still bottled water and compare.
Why does my espresso taste sour?
Sourness usually means the coffee is under-extracted. Try grinding finer or pulling a slightly longer shot. Soft water with low alkalinity can make acidity more noticeable, so you may need to go a little finer than a recipe written for harder water. See our espresso guide.
Do I need to descale my coffee machine in Scotland?
Usually less often than in hard-water parts of the UK, because soft water leaves less limescale. Always follow your machine manufacturer's instructions.
Sources
Drinking Water Quality Regulator for Scotland; Scottish Water factsheets on water hardness; Specialty Coffee Association, 25 Magazine, Issue 9.
