For UK specialty coffee in 2026 there are two answers worth your money. Sugar cane ethyl acetate, processed in Colombia, is the most common method on UK specialty shelves and the working roaster’s default. Swiss Water, processed in Canada, is the chemical free benchmark if the wording on the bag matters to you. CO2 is excellent but rare. Mountain Water is effectively Swiss Water made in Mexico. Methylene chloride is still legal, still in commodity decaf, and still not banned.
That is the short version. The longer version, with the catalogue numbers behind it, follows.
The five decaffeination methods
Every decaf you have ever bought used one of five processes. Four of them are specialty-grade. The fifth fills the supermarket shelves and almost certainly the instant jar in your kitchen.
Swiss Water Process (Canada)
Water and activated carbon, no solvent at any stage. Green beans are introduced to a flavour-saturated water solution called Green Coffee Extract that already holds every soluble compound in green coffee except caffeine. Caffeine diffuses out of the beans into the GCE because the GCE is caffeine-lean. Flavour compounds stay put because the GCE is already saturated with them. The loaded GCE then passes through activated carbon filters that trap caffeine and let the flavour molecules through. The cleaned GCE goes back into the loop for the next batch.
Invented in Switzerland in 1933, commercialised by Coffex S.A. in 1980, and run from Canada by Swiss Water Decaffeinated Coffee Inc. from 1988. Today it operates from a single plant in Delta, British Columbia. Removes 99.9% of caffeine. James Hoffmann’s blinded Decaf Project, widely cited in UK specialty circles, found Sugar Cane EA the overall favourite, with Swiss Water and Carbonic Natural CO2 performing similarly to each other, and Swiss Water notably picking up as the cup cooled.
For the four-step cycle in detail, see how Swiss Water decaffeination works.
Mountain Water Process (Mexico)
Same fundamental mechanism as Swiss Water. Water plus activated carbon, no solvent. The difference is the plant. Mountain Water is run by Descamex in Córdoba, Veracruz, using water sourced from Pico de Orizaba, Mexico’s highest peak. It is a separately owned brand from Swiss Water Inc., not a regional licensee.
Where Mountain Water differs in practice is openness. The Descamex model lets a small roaster send a single lot for processing under its own brand more easily than Swiss Water historically has, which is the structural reason Mountain Water keeps showing up in independent UK roaster line ups. The cup profile leans marginally lighter and brighter than Swiss Water, though that consensus comes from roaster reports rather than controlled testing.
One claim that circulates online says Mountain Water uses small amounts of methylene chloride in filtration. It does not. The claim originates from a single source and is contradicted by Descamex’s own documentation and every other processor reference. Mountain Water is mechanistically equivalent to Swiss Water, full stop.
Sugar cane ethyl acetate (Colombia)
The single method most likely to be in your specialty decaf if you bought it from a UK roaster in the last two years. Processed at the Descafecol plant in Manizales, the only decaffeination facility in Andean Colombia. Ethyl acetate is supplied by Sucroal SA in Palmira, made from sugarcane molasses through fermentation, ethanol production, and reaction with acetic acid. Food-grade, FDA-approved, identical in molecule to the ethyl acetate that occurs naturally in ripe fruit (it is part of what gives a ripe banana its smell).
The mechanism. Green coffee is steamed to remove silver skin and prime the bean structure. Hot water begins hydrolysing the caffeine, which sits bonded to chlorogenic acid salts inside the bean. The beans are then submerged in a wash of ethyl acetate and water. The EA bonds with caffeine and pulls it out. The wash is flushed and repeated until decaffeination hits the specialty target. A final steam pass removes residual EA. The beans dry to standard 10 to 12 percent shipping moisture and ship to the roaster.
The naming gets muddled. Older “ethyl acetate decaf” used synthetic EA derived from petrochemicals. Modern specialty sugar cane EA is plant-derived. The molecule is the same. The provenance is what specialty marketing emphasises. The “naturally decaffeinated” wording on most specialty bags is shorthand for this.
For the full picture, see the sugar cane method.
CO2 (supercritical carbon dioxide)
Discovered by Kurt Zosel at the Max Planck Institute for Coal Research in 1967 and patented for coffee in 1970. Green beans are pre-soaked and sealed into a pressure vessel. CO2 is pumped in at around 300 atmospheres and 65°C, conditions under which it becomes a supercritical fluid with properties between gas and liquid. The supercritical CO2 penetrates the bean and selectively dissolves caffeine. Coffee flavour compounds are largely insoluble in CO2 and stay in place. The caffeine-loaded CO2 then drops its caffeine in a scrubber and recirculates.
What CO2 does better than the water processes is hold onto lipids, which carry much of the aroma and the crema-forming compounds that matter for espresso. UK roasters who care about espresso decaf often pick CO2 for this reason. UK specialty CO2 decaf is supplied almost entirely by CR3-Kaffeeveredelung in Bremen, Germany, which runs the sub-critical liquid-CO2 variant branded as Sparkling Water Process.
Why it is rare. Capital cost. A pressurised CO2 plant is the most expensive of the four to build, which is why supply globally is small relative to water and EA methods.
A footnote for the careful reader. CR3 developed its sub-critical CO2 variant in 1988, running at lower temperature and pressure than the supercritical method. This is the process branded as Sparkling Water on UK packaging. Hoffmann’s Decaf Project used CR3 sub-critical CO2 (Carbonic Natural) as one of its four test variants. If you see “CR3 process” on a bag, that is what it means.
For the full picture, see how CO2 decaffeination works.
Methylene chloride (the European Method)
The fifth method, and the one specialty roasters refuse to use. Methylene chloride, also called dichloromethane or MC, is an organic solvent that binds to caffeine and is then evaporated off. Direct-solvent and indirect-solvent variants exist, the difference being whether MC contacts the bean directly or whether it works through a water bath. Both are MC.
The regulatory position, dated. The EU permits residual MC at no more than 2 mg/kg in roasted coffee, governed by Directive 2009/32/EC. The US FDA permits up to 10 ppm. The UK retained the EU limit by default after Brexit and has announced no separate action. In January 2024 the Environmental Defense Fund, Center for Environmental Health, Environmental Working Group, Breast Cancer Prevention Partners and consultant Lisa Lefferts filed a petition asking the FDA to remove the food use exemption that lets coffee processors continue to use MC. The FDA accepted the petition for review. Sixteen months in, as of May 2026, no decision. In April 2024 the US EPA finalised a ban on MC for most consumer and commercial uses under its TSCA authority. Food uses, including coffee decaffeination, fall under FDA jurisdiction and were not in scope of the EPA rule.
Specialty avoids MC on flavour and optics. Regulators agree the residue reaching the cup is negligible. The reason MC dominates supermarket and instant decaf is that it is the cheapest method at industrial scale.
For the full picture, see chemical decaffeination.
What “best” actually means
Comparing methods is only useful if you decide what you are comparing against. Five criteria worth weighing.
Flavour preservation. Subjective and stubborn to test. Hoffmann’s blinded Decaf Project found Sugar Cane EA the overall favourite, with Swiss Water and Carbonic Natural CO2 performing similarly to each other, and Swiss Water picking up as the cup cooled. The honest summary is that the gap between methods is smaller than the gap between a good roast and a bad one.
Chemical exposure. Water methods use no solvent. Sugar cane EA uses a plant-derived solvent that leaves trace residue. CO2 uses no chemical besides CO2 itself, which vents off as gas. MC leaves detectable residue at the regulatory limit, below the cup detection threshold but above zero.
Environmental cost. Water processes are water-intensive but closed loop. Sugar cane EA recovers and reuses solvent. CO2 recirculates the gas. MC produces hazardous waste that must be disposed of or recovered. No solid lifecycle comparison exists across all four, so anyone claiming a clean environmental winner is overreaching.
Availability on UK shelves. Sugar cane EA is the most common specialty method. Swiss Water is second. CO2 a distant third. Mountain Water sits with the smaller independents. Supermarket and instant decaf is overwhelmingly MC.
Price to the roaster. MC is cheapest. Sugar cane EA next. Swiss Water and Mountain Water in the middle. CO2 highest. The price gap is the structural reason CO2 stays rare in specialty.
The verdict by criterion
| Criterion | Winner | Note |
|---|---|---|
| Flavour, overall favourite | Sugar Cane EA | Hoffmann Decaf Project survey finding |
| Body and crema for espresso | CO2 | Lipid retention |
| Brightness and delicate aromatics | Mountain Water | Roaster consensus, subjective |
| Solvent free wording on the bag | Swiss Water and Mountain Water | The only methods that touch the bean with nothing but water |
| Availability on UK specialty shelves | Sugar cane EA | Most common method in the catalogue |
| Single-origin storytelling | Sugar cane EA | Single-country (Colombia) processing |
| Environmental story | Genuine tie | No solid lifecycle comparison exists |
| Cheapest to produce | Methylene chloride | Why supermarket decaf is MC |
| Best overall for a UK specialty buyer in 2026 | Sugar cane EA | Best flavour-to-availability ratio |
What UK specialty roasters actually use
Across the UK specialty decafs catalogued on decaffeinate.co.uk, sugar cane ethyl acetate is the most common method by a clear margin, followed by Swiss Water, then Mountain Water and CO2. A small number of listings do not declare a method, which usually means a smaller roaster has not surfaced the information rather than that the method is unusual.
The pattern by roaster.
- Sugar cane EA. Hundred House Coffee, Clifton Coffee Roasters, Dear Green Coffee, Sustain Coffee, The Roasting Party, Colombia Coffee Roasters.
- Swiss Water. Apostle Coffee, Bad Hand Coffee, Belfast Coffee Roasters, York Coffee Emporium, Caribe Coffee, The Studio Coffee Roasters, Artisan Roast, Insurgence Coffee.
- Mountain Water. Anvil Coffee, Rounton Coffee, The Studio Coffee Roasters.
- CO2. Monkey Board Coffee, The Studio Coffee Roasters (Sparkling Water label).
For supermarket and instant decaf, expect MC almost without exception. Roasters who care about the method usually say so on the bag. Roasters who do not say almost always have a reason.
Buying decaf in the UK: what to look for on the bag
A practical reading guide for label phrasing.
- “Sugar cane decaf” / “EA decaf” / “Colombia decaf, ethyl acetate” is sugar cane EA from Descafecol. The most common specialty option.
- “Swiss Water” / “SWP” is the trademarked Canadian water process. The phrase can only be used if the beans were processed by Swiss Water Inc.
- “Mountain Water” / “MWP” is the Descamex Mexican water process. Different plant, different brand, same fundamental method.
- “CO2” / “supercritical CO2” is the pressurised CO2 process; in UK specialty this almost always means CR3 (Bremen). “Sparkling Water” is CR3’s sub-critical liquid-CO2 variant. Same plant, same family, different branding.
- “Naturally decaffeinated” with no further detail is ambiguous. On a specialty bag it almost always means sugar cane EA. On a commodity bag it can mean MC dressed up. Ask the roaster if you care.
- No method named at all on a supermarket bag is almost always MC. Safe to drink, not specialty-grade flavour.
The FAQs the SERP keeps fudging
Answering the questions the existing top ten skirts.
Is methylene chloride decaf actually being banned? No, and not soon. The January 2024 FDA petition is still under review sixteen months in. The April 2024 EPA ban on consumer and commercial methylene chloride uses under TSCA does not cover food uses, which sit under FDA jurisdiction. The EU has set its 2 mg/kg residue limit and shows no sign of moving. The UK inherited the EU limit and has announced nothing of its own. If you are waiting for a ban to make your decision, you will be waiting for a while.
Are Swiss Water and Mountain Water really different? Mechanistically, no. The water and activated carbon principle is the same. Commercially, yes. Two separately owned plants, two separately licensed brands, two different water sources. The “essentially the same” line some roaster blogs use is fine as a simplification but misses why Mountain Water keeps showing up in independent UK lineups (the open processing model). Hoffmann’s Decaf Project did not test Mountain Water, so its findings on Swiss Water do not translate directly. The two should perform comparably given the shared mechanism.
Is sugar cane EA actually natural? The ethyl acetate molecule itself does occur in nature, particularly in ripe fruit. The EA used at Descafecol is fermented from sugarcane molasses rather than synthesised from petrochemicals. Whether that satisfies your personal “natural” threshold depends on where you draw the line. Chemically, the EA on the bean is the same molecule whether it came from sugarcane or petrochemicals. Ethically, the sugarcane sourcing keeps value in Colombia. Both arguments are honest.
Why does some CO2 decaf say “Sparkling Water” on the bag? Sparkling Water Process is the brand name used by CR3 in Bremen, Germany, for their sub-critical liquid-CO2 method (developed in 1988). It is distinct from the classical supercritical CO2 method developed from Zosel’s 1970 patent, although both belong to the broader CO2 family.
Does the decaffeination method change the caffeine content? Not meaningfully. All four specialty methods reach 99.7 to 99.9% caffeine removal. Residual caffeine works out to roughly 2 to 5 mg per cup against 80 to 100 mg in a regular cup. The choice between methods is about flavour, ethics and price.
Browse the catalogue
Browse the UK specialty decafs in our catalogue, filterable by method, roaster and flavour profile. The directory covers the lot.