Water for Espresso Machines: What to Use and Why It Matters
Espresso is mostly water, so the water you use changes how it tastes. It also affects how long your machine lasts, because minerals in hard water build up as scale inside the machine.
This guide explains what good espresso water looks like, how to test yours, and how to choose a filter. For water costs, see our separate guide to coffee shop water costs.
The SCA water standard
The Specialty Coffee Association (then the SCAA) published a standard for water used to brew specialty coffee. Clive Coffee reproduces it:
| Characteristic | Target | Acceptable range |
|---|---|---|
| Odor | Clean, fresh, odor-free | |
| Color | Clear | |
| Total chlorine | 0 mg/L | |
| Total dissolved solids (TDS) | 150 mg/L | 75 to 250 mg/L |
| Calcium hardness | 68 mg/L (4 grains) | 17 to 85 mg/L (1 to 5 grains) |
| Total alkalinity | 40 mg/L | At or near 40 mg/L |
| pH | 7.0 | 6.5 to 7.5 |
| Sodium | 10 mg/L | At or near 10 mg/L |
In plain terms: good espresso water has no chlorine taste or smell, a moderate amount of minerals, not too much hardness, and a neutral pH.
Beans made for espresso and milk drinks
For lattes, cappuccinos and iced coffee, try our Arabica-Robusta Blend or bold Robusta, roasted daily and ground to order for espresso or moka pot.
Shop the Blend →Why hard water is a problem
Clive Coffee explains that water high in bicarbonate both flattens flavor and creates scale that can damage boilers and group heads. That’s why TESDA’s barista standard includes checking the water softener filter regularly as part of machine maintenance.
Why very soft or pure water isn’t ideal either
- Water with almost no minerals, such as pure reverse osmosis water, falls below the SCA’s acceptable TDS range of 75 to 250 mg/L.
- Sodium-softened water swaps hardness minerals for sodium. Clive Coffee notes that it doesn’t improve taste.
- Distilled water also falls below the range. Check your machine’s manual before using it.
How to test your water
- Start with a TDS meter. It’s cheap and shows the total mineral content. Compare the reading with the 75 to 250 mg/L range.
- Test hardness with water hardness test strips, or ask your filter supplier to test it.
- Smell and taste the water. Any chlorine smell should be removed with a carbon filter.
- Test again from time to time, because water supply can change.
Choosing a filter for a café
Seven Miles advises testing your water before choosing a filter, because the right one depends on what’s in it:
| Water test result | Usually needs |
|---|---|
| Within range, but tastes or smells of chlorine | A carbon filter |
| Hard water | A filter with scale protection, as recommended by your machine supplier |
| Very high TDS or poor-quality supply | Reverse osmosis with remineralization, to put back a balanced amount of minerals |
Whatever you choose, change cartridges on schedule. A filter that’s past its capacity stops protecting the machine. Ask your espresso machine supplier which filter their warranty requires.
At home
For a home machine, filtered water from a jug filter is a big improvement over untreated tap water in many areas. Check that the bottled or filtered water you use isn’t extremely low in minerals. Our article on water filter jugs for coffee has more.
Related lessons
See espresso machine parts, how to clean an espresso machine and choosing a commercial espresso machine. Cafés buying 10 kg or more of coffee can see wholesale pricing. More lessons are in the Caffeine Brothers Coffee Academy.
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