Where water factors into quality

When water is used to brew coffee, it isn't just a carrier. It comes into direct contact with the coffee and dissolves some of the compounds from the grounds into the drink. So water quality can affect both extraction and the final sensory experience.

The SCA has previously published water requirements for brewing in earlier standards documents, covering criteria like odor, color, chlorine, total dissolved solids, calcium hardness, alkalinity, pH, and sodium. An SCA resource also explains that the minerals in water affect its solvent properties and therefore how compounds in coffee get extracted. Specific figures should be tied to their correct document and version — not every old recommendation table should be treated as one single current standard.

More recent research continues to show that water composition can change extraction behavior and the character of the resulting drink. So if a “clean coffee” claim overlooks brewing water, the quality story is still missing a link.

“Clean water” and “water suited to brewing” aren't quite the same statement

Water can meet safety requirements without necessarily producing the same brewing result as every other water source. The reason lies in dissolved composition. Hardness, alkalinity, and minerals can all change how water interacts with the compounds in coffee.

The SCA explains that hydrogen carbonate has acid-buffering capacity, so alkalinity can noticeably affect how sour a coffee tastes. Minerals like calcium and magnesium also play a role in how water interacts with the extracted compounds. A study cited by the SCA found that alkalinity and brew ratio can change how much water's effect on acidity shows up across different brewing methods.

So “clean water” and “water suited to brewing” need to be treated as two separate questions. The first asks whether the water meets safety and hygiene requirements. The second asks whether its composition suits the brewing and sensory goals at hand. Both can be true at once, but one doesn't automatically prove the other.

Water used for cleaning is a different story altogether

Water used to wash equipment and surfaces that touch coffee serves a different purpose from water that goes directly into the drink. Even so, if water touches a food-contact surface, its quality still needs to be controlled to match that purpose.

The key point is that the risk doesn't lie only in the water source itself. Water can leave behind minerals, odors, or other residues on a surface if rinsing and drying aren't handled properly. Water that's suitable for one step shouldn't be treated as proof that every other step has been properly controlled.

In a production facility, it's worth clearly recording what each stream of water is used for. Brewing water is controlled against the goals of the drink. Cleaning water is assessed against hygiene requirements and surface-contact needs. Even if both streams come from the same source, the records should still distinguish their purposes to avoid drawing conclusions that go too far.

Giving water its proper place within “clean”

Water is part of the “clean” story, but not in the sense that simply saying “clean water” resolves everything. There are at least three layers worth separating: the safety and hygiene of the water source, the chemical composition suited to brewing, and the water's suitability for the cleaning step it's used in.

This framing is especially useful when assessing the quality of a cup of coffee. If a drink tastes off, the beans shouldn't be the only suspect. Water, equipment, temperature, brew ratio, and technique can all contribute. Suitable water removes one major variable from the brewing process, but it can't replace controlling the rest.

So bringing water into the “clean coffee” conversation isn't about stretching the concept arbitrarily wider. The point is to ask the right question at the right stage: is the water suitable for direct contact with the drink, does its composition suit the brewing goal, and is the water used for cleaning controlled for its own purpose?

References

• Specialty Coffee Association — Water and the Taste of Coffee — https://sca.coffee/sca-news/news-from-our-partners/water-and-the-taste-of-coffee-ay9gh
• Specialty Coffee Association — Water and Coffee Acidity: How to Adapt Water Recipes for Different Extraction Methods — https://sca.coffee/sca-news/25/issue-9/english/water-and-coffee-acidity-how-to-adapt-water-recipes-for-different-extraction-methods-25-magazine-issue-9-pxjby
• Exploring the impacts and mechanisms of water on the taste extractions and perceptions of coffee brews: A case study in filter brewing — Journal of Food Composition and Analysis, 2025 — https://www.sciencedirect.com/science/article/pii/S0889157525008026