{ "id": "filter-coffee-machines", "url": "https://coffearium.org/entries/filter-coffee-machines/", "license": "CC-BY-4.0", "title": "Filter coffee machines", "summary": "An automatic drip machine heats water in a tube, lifts it with steam bubbles and sprays it over ground coffee in a paper filter. The entry covers its parts, its test standards and the rules on holding and switch-off.", "domain": "equipment", "kind": "Equipment", "stage": "brew", "topics": [ "equipment", "sustainability" ], "topicSections": { "sustainability": { "id": "energy-use-and-switch-off-rules", "label": "Energy use and switch-off rules" } }, "lang": "en", "status": "verified", "reviewer": "Coffearium verification pass", "lastVerified": "2026-10-27T00:00:00.000Z", "literatureSearched": "2026-10-27T00:00:00.000Z", "updated": "2026-10-27T00:00:00.000Z", "added": "2026-10-27T00:00:00.000Z", "brief": [ "An automatic drip machine heats water in a tube in its base; steam pushes it up a riser in spurts, and a one-way valve stops it flowing back to the reservoir.3,4", "The Specialty Coffee Association (SCA) home-brewer standard, SCA 310-2021, requires a slurry of 90–96 °C from the time 33% of the water has been sprayed.1", "At its test ratio of 55 g of coffee per 1.000 kg of water, SCA 310-2021 requires 1.15–1.55% total dissolved solids (TDS) and sets no brew-time limit.1", "Since 2015, EU ecodesign rules (now Regulation 2023/826) have required household drip machines to switch off within 5 min of brewing with an insulated jug, 40 min with a non-insulated one.8,10", "In a 2025 study, paper-filtered drip coffee held a median of 12 mg/L cafestol; workplace machines brewing through metal filters, 176 mg/L.7" ], "quickFacts": [ { "label": "How water moves", "value": "Steam bubbles lift boiling water up a riser in spurts; a check valve blocks the way back" }, { "label": "Slurry (SCA 310-2021)", "value": "90–96 °C from 33% of the water sprayed to the end of the cycle" }, { "label": "Strength (SCA 310-2021)", "value": "1.15–1.55% TDS at 55 g coffee per 1.000 kg water; uniformity rating ≥60" }, { "label": "Heated plate (SCA 310-2021)", "value": "80–85 °C for the first 30 min of holding; never above 85 °C from heating" }, { "label": "EU switch-off (Reg. 801/2013; 2023/826)", "value": "≤5 min after brewing (insulated jug); ≤40 min (non-insulated jug)" }, { "label": "One measured machine", "value": "100 g coffee, 1,800 mL brew, ≈90 °C, 348 s, paper filter (Gloess et al. 2013)" }, { "label": "Test methods", "value": "IEC 60661 (measurement methods, no requirements)" } ], "aka": [ "Automatic drip machine", "Drip coffee maker", "Filter coffee maker" ], "linkTerms": [ "drip filter machine", "drip filter coffee machine", "automatic drip machine", "drip coffee maker", "filter coffee maker", "warming plate", "keep-warm plate", "insulated jug", "thermal carafe", "filter coffee machine", "drip brewer", "drip coffee", "batch brew", "batch brewer" ], "related": [ "brew-methods", "pour-over-technique", "brew-temperature", "brew-ratio-and-strength", "extraction-yield-and-tds", "brewing-control-chart", "coffee-oil", "grinding", "water-treatment", "carbon-footprint-of-coffee", "espresso-machine", "history-of-brewing" ], "contested": [], "corrections": [ { "date": "2026-10-27T00:00:00.000Z", "change": "The EU switch-off delays are now sourced to the text of Regulation (EU) 2023/826, which applies from 9 May 2025 and keeps 5, 40 and 30 min; the rules of Regulation 801/2013 are given in the past tense, and the energy-policy database summary (former source 11) was removed.", "reason": "Verification against the regulation's Annex III and Annex IV; the entry had left the current delay times open." }, { "date": "2026-10-27T00:00:00.000Z", "change": "Added that the 2013 study's table heads the 1,800 mL as extract but its caption as water, with a check that the reported 19% yield fits 1,800 mL of brew.", "reason": "Verification against the paper's Table 1 and its caption." } ], "sources": [ { "id": "s1", "title": "SCA Standard 310-2021 Home Coffee Brewers: Specifications and Test Methods", "authors": "Specialty Coffee Association", "year": 2021, "publisher": "Specialty Coffee Association (document © 2022)", "url": "https://sca.coffee/s/SCA_Standard_310-2021.pdf", "tier": "A/B", "tierNote": "A for what the standard itself specifies (slurry and holding temperatures, strength target, uniformity rating, test coffee, water and grind); B otherwise. It covers electrical filter brewers for home use and excludes manual pour-over devices, French-press-style brewers and pod or capsule brewers.", "quote": "shall reach a temperature in the 90 to 96°C range by the moment when 33% of the water mass has been sprayed", "quotes": [ { "text": "shall be a brew strength of 1.15-1.55% at the standard brew ratio.", "for": "strength target" }, { "text": "Brewers shall achieve a uniformity of extraction rating of 60 or above, tested at full capacity.", "for": "uniformity rating of 60 or above" }, { "text": "The index rating is 0-100, with 100 indicating perfect uniformity of extraction.", "for": "scale of the uniformity rating" }, { "text": "at no point should the temperature of the coffee increase above 85°C due to a heating element.", "for": "heated holding limit" }, { "text": "pod/capsule brewers are excluded from this standard.", "for": "scope" }, { "text": "Coffees at least of 1-1.5 weeks off-roast shall be utilized to assure consistent brewing.", "for": "test coffee rest" }, { "text": "There are no normative references for this standard.", "for": "no reference to IEC 60661" } ], "scope": { "claim": "guidance", "context": "Certification specification and test methods for electrical filter brewers for home use; requirements, not measurements.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s2", "title": "IEC 60661 – Methods for measuring the performance of electric household coffee makers (edition 2.2, consolidated with amendments 1 and 2)", "authors": "International Electrotechnical Commission", "year": 2006, "publisher": "International Electrotechnical Commission (IEC); preview of the 2006-02 consolidated edition via VDE Verlag", "url": "https://www.vde-verlag.de/iec-normen/preview-pdf/info_iec60661{ed2.2}b.pdf", "tier": "A", "quote": "This International standard applies to electric coffee makers for household and similar use.", "quotes": [ { "text": "This standard is concerned neither with safety nor performance requirements.", "for": "methods only, no requirements" } ], "scope": { "claim": "definition", "context": "Scope clause and table of contents of the standard (public preview); the test procedures themselves were not consulted.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s3", "title": "Coffee maker with improved hot water pump (US Patent 3,996,846)", "authors": "Hupf, C. J. (assignee Regal Ware Inc.)", "year": 1976, "publisher": "United States Patent Office; filed 3 December 1975, granted 14 December 1976", "url": "https://patents.google.com/patent/US3996846", "tier": "A", "quote": "As steam forms in heating chamber 44, it forces the hot water therein upwardly", "quotes": [ { "text": "pumps hot water in periodic spurts", "for": "water lifted in spurts" }, { "text": "to prevent exit of water therethrough from heating chamber 44", "for": "one-way valve" }, { "text": "to keep the coffee in coffee pot 16 warm", "for": "heater under the pot stand" } ], "scope": { "claim": "description", "context": "Patent description of one drip coffee maker design; construction only.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s4", "title": "Electric coffee maker (US Patent 4,744,291)", "authors": "Wallin, G. W. (assignor to Scovill Inc.; later Hamilton Beach Inc.)", "publisher": "United States Patent and Trademark Office; application 06/342,924", "url": "https://patents.google.com/patent/US4744291", "tier": "A", "quote": "The receiver sits on a keep-warm plate heated by the flow-through heater.", "quotes": [ { "text": "steam is developed creating pressure in the water heater, driving the water up the riser", "for": "steam drives water up the riser (prior-art description)" }, { "text": "the ball continues to operate as a check valve blocking altogether flow of liquid back up into the reservoir 14", "for": "ball check valve" } ], "scope": { "claim": "description", "context": "Patent describing the conventional single-pass drip coffee maker (prior art) and a modified valve; construction only.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s5", "title": "The Brew – Extracting for Excellence", "authors": "Mestdagh, F.; Glabasnia, A.; Giuliano, P.", "year": 2017, "publisher": "In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 15, pp. 355–380", "url": "https://doi.org/10.1016/B978-0-12-803520-7.00015-3", "doi": "10.1016/B978-0-12-803520-7.00015-3", "tier": "B", "quote": "In contrast, filter paper is very efficiently absorbing oil and the corresponding brews are low in fat content.", "quotes": [ { "text": "Water is applied manually or by an automatic drip filter machine, some of which can be programmed to deliver specific amounts of water at specific temperatures over time.", "for": "programmable drip machines" }, { "text": "The pressure therefore is very limited depending on the water column that builds up above the coffee bed.", "for": "almost no pressure on the bed" } ], "scope": { "claim": "description", "context": "Textbook chapter on brewing; general description without measurements for drip machines.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s6", "title": "Comparison of nine common coffee extraction methods: instrumental and sensory analysis", "authors": "Gloess, A. N.; Schönbächler, B.; Klopprogge, B.; D’Ambrosio, L.; Chatelain, K.; Bongartz, A.; Strittmatter, A.; Rast, M.; Yeretzian, C.", "year": 2013, "publisher": "European Food Research and Technology 236, 607–627", "url": "https://digitalcollection.zhaw.ch/bitstream/11475/4251/2/2013_Gloess-etal_Comparison-of-nine-common-coffee-extraction-methods.pdf", "doi": "10.1007/s00217-013-1917-x", "tier": "A", "quote": "Filter coffee showed a relatively weak but very well-balanced flavor profile.", "quotes": [ { "text": "even filter coffee showed a relatively high extraction yield of 19 %", "for": "extraction yield of 19%" }, { "text": "the volume of water per cup or jug in milliliters", "for": "table caption wording (column heading reads volume of extract)" } ], "scope": { "claim": "finding", "context": "Laboratory comparison in Switzerland; one coffee, one recipe per method; filter coffee from one commercial filter machine with a paper filter.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s7", "title": "Cafestol and kahweol concentrations in workplace machine coffee compared with conventional brewing methods", "authors": "Orrje, E.; Fristedt, R.; Rosqvist, F.; Landberg, R.; Iggman, D.", "year": 2025, "publisher": "Nutrition, Metabolism and Cardiovascular Diseases 35, 103933", "url": "https://research.chalmers.se/publication/545621/file/545621_Fulltext.pdf", "doi": "10.1016/j.numecd.2025.103933", "tier": "A", "quote": "Boiled coffee had high concentrations of cafestol and kahweol, 939 mg/L and 678 mg/L, but having it poured through a fabric filter reduced the concentrations to 28 and 21 mg/L.", "quotes": [ { "text": "Drip-brewed coffee was prepared with a common household coffee brewer", "for": "household drip brewer" }, { "text": "as the hot water mixes with the coffee and passes a metal filter.", "for": "workplace brewing machines use a metal filter" }, { "text": "with two different paper filters from commercially available brands", "for": "normal and perforated paper filters" } ], "scope": { "claim": "finding", "context": "Brews sampled in Sweden (workplace machines, n = 14; home brews of five coffees with two paper filter types); LC–MS measurement.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s8", "title": "Commission Regulation (EU) No 801/2013 of 22 August 2013 amending Regulation (EC) No 1275/2008 with regard to ecodesign requirements for standby, off mode electric power consumption and networked standby of electrical and electronic household and office equipment, and amending Regulation (EC) No 642/2009", "authors": "European Commission", "year": 2013, "publisher": "Official Journal of the European Union L 225, 23 August 2013 (copy hosted by the Danish Energy Agency)", "url": "https://ens.dk/media/961/download", "tier": "A", "quote": "for domestic drip filter coffee machines storing the coffee in a non-insulated jug, a maximum of 40 minutes", "quotes": [ { "text": "a maximum of five minutes after completion of the last brewing cycle", "for": "insulated jug, 5 min" }, { "text": "household coffee machine which uses percolation to extract the coffee", "for": "definition of a drip filter household coffee machine" }, { "text": "Point 6 of Annex II shall apply as from 1 January 2015.", "for": "date of application" } ], "scope": { "claim": "guidance", "context": "EU ecodesign regulation; legal requirement for household coffee machines placed on the EU market from 1 January 2015 until its parent regulation was repealed on 9 May 2025.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s9", "title": "If the 40 minutes is interrupted by pouring coffee for example would this reset the timing and would then another 40 minutes be applied? (FAQ on Regulation (EC) No 1275/2008)", "authors": "European Commission", "publisher": "European Commission, Energy-efficient products", "url": "https://energy-efficient-products.ec.europa.eu/faqs-0/if-40-minutes-interrupted-pouring-coffee-example-would-reset-timing-and-would-then-another-40_en", "tier": "A", "quote": "The 40 minutes are not be interrupted by lifting the coffee pot.", "quotes": [], "scope": { "claim": "guidance", "context": "Commission answer on how the 40-minute delay for non-insulated jugs is applied.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s10", "title": "Commission Regulation (EU) 2023/826 of 17 April 2023 laying down ecodesign requirements for off mode, standby mode, and networked standby energy consumption of electrical and electronic household and office equipment pursuant to Directive 2009/125/EC of the European Parliament and of the Council and repealing Commission Regulations (EC) No 1275/2008 and (EC) No 107/2009", "authors": "European Commission", "year": 2023, "publisher": "Official Journal of the European Union (text via EUR-Lex)", "url": "https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32023R0826", "tier": "A", "quote": "for drip filter household coffee machines storing the coffee in a non-insulated jug, a maximum of 40 minutes;", "quotes": [ { "text": "for drip filter household coffee machines storing the coffee in an insulated jug, a maximum of five minutes;", "for": "insulated jug, 5 min" }, { "text": "for household coffee machines other than drip filter household coffee machines, a maximum of 30 minutes.", "for": "other household coffee machines, 30 min" }, { "text": "Regulation (EC) No 1275/2008 is repealed with effect from 9 May 2025.", "for": "repeal of Regulation 1275/2008" }, { "text": "It shall apply from 9 May 2025.", "for": "date of application" }, { "text": "For all types of household coffee machines, the measurements shall be performed after completion of the last brewing cycle", "for": "delay counted from the last brew cycle" } ], "scope": { "claim": "guidance", "context": "EU ecodesign regulation in force from 9 May 2025; Annex III point 2(b) (power management of household coffee machines) and Annex IV point (d) consulted.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s11", "title": "Life cycle assessment of spray dried soluble coffee and comparison with alternatives (drip filter and capsule espresso)", "authors": "Humbert, S.; Loerincik, Y.; Rossi, V.; Margni, M.; Jolliet, O.", "year": 2009, "publisher": "Journal of Cleaner Production 17(15), 1351–1358", "url": "https://documents.epfl.ch/groups/m/me/mediacomfiles/www/Humbert%20et%20al%202009%20-%20LCA%20Coffee.pdf", "doi": "10.1016/j.jclepro.2009.04.011", "tier": "A", "quote": "The time the water or coffee is kept warm and the number of coffees prepared per machine and per day are the two key factors for capsule espresso and drip filter alternatives.", "quotes": [ { "text": "0.125 kWh/l and 0.001 kWh/min for the stand-by (own measurements)", "for": "heating and stand-by energy assumed" }, { "text": "drip filter coffee, that represents the most energy intensive option.", "for": "drip filter most energy-intensive of the three" } ], "scope": { "claim": "finding", "context": "Life cycle assessment of a 1 dl cup at home, European electricity mix; drip filter machine, 2 cups a day, 300 days a year over 10 years, 2 h stand-by a day; energy = non-renewable primary energy.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s12", "title": "75th anniversary of death of Melitta Bentz", "authors": "Potthast, J. B. (Deutsches Patent- und Markenamt, DPMA)", "publisher": "German Patent and Trade Mark Office", "url": "https://dpma.de/english/our_office/publications/ingeniouswomen/melittabentz/index.html", "tier": "A", "quote": "registered it as a utility model with the Imperial Patent Office on 20 June 1908", "quotes": [], "scope": { "claim": "data", "context": "Patent office account of the registration of the first paper coffee filter (Dresden, Germany).", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" }, { "id": "s13", "title": "We Consumers – Tastes, Rituals, and Waves", "authors": "Morris, J.", "year": 2017, "publisher": "In: Folmer, B. (ed.), The Craft and Science of Coffee, Academic Press, ch. 19", "url": "https://doi.org/10.1016/B978-0-12-803520-7.00019-0", "doi": "10.1016/B978-0-12-803520-7.00019-0", "tier": "B", "quote": "served out of the pour over jugs bulk brewed and left on the hotplate, that came to define the taste of the American", "quotes": [], "scope": { "claim": "description", "context": "Historical account of post-war coffee consumption in the United States; no measurements.", "checked": "2026-10-27T00:00:00.000Z" }, "accessed": "2026-10-27T00:00:00.000Z" } ], "markdown": "## What a filter machine does\n\nA filter coffee machine, or automatic drip machine, does the pouring of a pour-over by itself.5 It heats the water and delivers it over a bed of ground coffee in a filter.5 The brew drips through the filter into a jug below.5 EU law defines a drip filter household coffee machine as one that uses percolation to extract the coffee.8\n\nWater passes through the bed mainly by gravity, so the pressure on the bed is very low.5 According to a coffee science textbook, some machines can be programmed to deliver set amounts of water at set temperatures over time.5 How percolation differs from immersion, and how grind and bed shape act, is set out in the brew methods entry. The hand-poured version is covered in [Pour-over technique](/entries/pour-over-technique/).\n\n## Inside the machine\n\nMost of the work is done by one heater and one valve. Two patents describe the design.3,4\n\n- **Reservoir to heater.** Cold water runs from the reservoir through a one-way (check) valve into a heating tube in the base.3,4\n- **Steam lift.** The heater brings the water in the tube to the boil.3 As steam forms, it pushes the hot water up a riser tube.3,4 One patent calls this assembly a hot water pump that works in periodic spurts.3\n- **No way back.** The steam pressure closes the valve, so water cannot return to the reservoir.3,4\n- **Over the bed.** At the top, the water runs along an arm and falls from an outlet onto the coffee in the basket.3,4 SCA 310-2021 calls this water “sprayed”.1\n- **Keeping warm.** In one patented design the same flow-through heater also warms the plate under the jug.4 Another uses a separate heater under the pot stand.3\n\n
\n
\n
    \n
  1. Water reservoir. Holds the cold water for one brew cycle.3,4
    2. \n
  2. One-way valve. A check valve between reservoir and heater; steam pressure closes it.3,4
    3. \n
  3. Heating element and water tube. Brings the water in the tube to the boil.3,4
    4. \n
  4. Riser tube. Steam bubbles push the hot water up in spurts.3,4
    5. \n
  5. Outlet over the basket. Lets the water fall onto the coffee bed.1,3
    6. \n
  6. Filter basket. Holds the paper filter and the coffee bed; the brew drips out below.1,5
    7. \n
  7. Jug. The holding receptacle that receives the brew.1
    8. \n
  8. Warming plate. Keeps the brew in the jug hot; heated by the flow-through heater in one design.4
    9. \n
\n
An automatic drip machine cut along its centre line. The dashed line follows the water from the reservoir to the jug. Schematic, not to scale.
\n
\n\n## Keeping the coffee hot\n\nAfter brewing, the coffee waits in the jug. Some machines keep the jug on a heated plate.3,4 Others brew into an insulated jug.8 EU rules treat the two differently (see [Energy use and switch-off rules](#energy-use-and-switch-off-rules)).8\n\nSCA 310-2021 limits a heated plate.1 During the first 30 min of holding, the coffee must stay at 80–85 °C.1 The heating element must never raise it above 85 °C.1 The standard sets no requirement for unheated jugs.1\n\nWhat long holding does to flavour has not been measured in any study consulted for this entry. A coffee history chapter links the taste of the American “cup of Joe” to jugs that were bulk brewed and left on the hotplate.13 That is a historical account, not a sensory test.\n\n## Paper, metal and the cup\n\nThe filter decides how much coffee oil reaches the cup. According to a brewing textbook, filter paper absorbs oil very efficiently, so paper-filtered brews are low in fat.5 Unfiltered coffee also carries the cholesterol-raising diterpenes cafestol and kahweol.7\n\nIn a 2025 Swedish study, home-brewed, paper-filtered drip coffee held a median of 12 mg/L cafestol.7 Workplace brewing machines, which pass the water through a metal filter, gave a median of 176 mg/L.7 No study consulted for this entry measured drip coffee brewed through a permanent metal filter. The coffee oil entry covers diterpenes in depth.\n\n\n\n## What SCA 310-2021 specifies\n\nSCA 310-2021 covers electrical filter brewers for home use.1 It excludes manual pour-over devices, French-press-style brewers, pod and capsule brewers, home espresso machines and pressurised brewers.1 It is a certification test, so its values are requirements, not measurements of machines on sale.1\n\n**Test conditions.** The test uses 100% arabica coffee in the medium roast range (#55 to #65 on the SCA roast colour tiles), rested at least 1–1.5 weeks after roasting.1 The water is fresh and cold, at 17 ± 3 °C, and must meet the SCA water standard: calcium hardness 50–175 ppm, alkalinity 40–70 ppm (both as CaCO₃) and pH 6–8, as stated in the standard.1 The brew ratio is 55 g of coffee per 1.000 kg of water.1 The grind is defined by sieve fractions, one specification for conical baskets and a coarser one for flat baskets.1\n\n**Temperature.** The slurry must reach 90–96 °C by the time 33% of the water has been sprayed and stay in that range for the rest of the cycle.1 How the slurry is measured, and how this window compares with other standards, is set out in the brew temperature entry.\n\n**Strength and uniformity.** At the test ratio, the brew must reach 1.15–1.55% TDS.1 Brewers must meet these targets at full capacity.1 The standard also rates how evenly the bed was extracted.1 Samples taken through the full depth of the spent bed from the outside, middle and inside areas are dried and their residual soluble solids compared.1 For each pair of areas, the smaller value is divided by the larger and multiplied by 100; the three factors are averaged.1 The rating runs from 0 to 100, where 100 means perfectly uniform extraction; a brewer must score 60 or above at full capacity.1\n\n**Repeatability.** At least five brew cycles are run at full capacity on each of three brewer units; the uniformity test is repeated three times on one unit.1 Brewers holding more than 1 kg of water are also tested at 1 kg.1 The basket must hold enough coffee for a full jug without overflowing as the grounds swell.1\n\n**Time.** The standard defines the operation time, from the moment the user starts the cycle, but sets no limit on total brew time.1\n\n
\n
\n
Temperatures along the path of a home filter machine: the test water, the slurry and the heated plate as specified in SCA 310-20211, and the water temperature reported for one machine in a 2013 study.6 SCA rows are requirements, not measurements; measuring points differ.
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\n\n## Test methods: IEC 60661\n\nThe International Electrotechnical Commission (IEC) standard IEC 60661 describes how to measure the performance of electric coffee makers for household and similar use.2 It sets no safety or performance requirements; it only states which characteristics matter to users and how to measure them.2 Its methods are written for percolators, filter coffee makers and espresso makers.2\n\nThe edition consulted (2.2, 2006) lists, among others, measurements of the quantity of coffee made, the time to prepare the maximum and minimum quantity, the temperature of the coffee, residual water, quality of the coffee, a descaling test and energy consumption.2 The standard warns that its methods are more reliable for comparing several appliances in one laboratory at about the same time than for testing single appliances in different laboratories.2 SCA 310-2021 does not refer to it; it has no normative references.1 The test procedures of IEC 60661 themselves were not consulted for this entry, so no values from them are given.\n\n## What one machine measured\n\nAmong the studies consulted, one reports a drip machine’s brewing conditions and results in detail. In a 2013 comparison of nine methods, a filter machine brewed 100 g of coffee into 1,800 mL of brew at about 90 °C in 348 s, through a paper filter.6 The brew had 1.03% total solids, the lowest of all methods, and an extraction yield of 19%.6 It also had the least caffeine per sip, 4.7 mg per 10 mL.6 The panel found its flavour relatively weak but very well balanced.6\n\nThe paper’s table heads the 1,800 mL column as volume of extract, its caption as volume of water.6 1.03% of 1,800 g of brew is about 18.5 g of solids, or 18.5% of the 100 g dose, close to the reported 19%; with 1,800 g of water, less brew and a lower yield would follow (our calculation, assuming a brew density of about 1 g/mL). We therefore read 1,800 mL as the volume of brew.\n\nThe total solids were measured by drying, not with a refractometer. They cannot be set directly against the 1.15–1.55% TDS target of SCA 310-2021, which also uses a different ratio basis (coffee per kilogram of water, not per litre of brew).1,6 No study consulted for this entry measured slurry temperature or uniformity in machines on sale against the SCA requirements.\n\n## Filter type and diterpenes\n\nThe 2025 study brewed five coffees in a household drip brewer, about 7 g of coffee per 1 dL of water, each with a normal and a perforated (“aroma”) paper filter.7 The means did not differ significantly between the two filter types (P = 0.43 and 0.52).7\n\n| Brew | Cafestol (mg/L) | Kahweol (mg/L) | Source |\n|---|---|---|---|\n| Drip, paper-filtered, all home brews (n = 5) | 12 (4–24), median and range | 8 (3–19) | Orrje et al.7 |\n| Drip, normal paper filters | 6.1 (4.2–23.8); mean 9.7 | 4.5 (2.8–19.0); mean 7.4 | Orrje et al.7 |\n| Drip, perforated paper filters | 15.8 (8.2–17.0); mean 13.2 | 11.8 (5.5–12.9); mean 9.7 | Orrje et al.7 |\n| Workplace brewing machines, metal filter (n = 11) | 176 (24–444), median and range | 142 (18–434) | Orrje et al.7 |\n| Boiled coffee | 939 | 678 | Orrje et al.7 |\n\nThe values for other brew methods are in the brew methods entry. The health side is not covered here.\n\n## Energy use and switch-off rules\n\n**EU switch-off rules.** From 1 January 2015, EU Regulation 801/2013 limited how long a household coffee machine could stay on after brewing.8 A drip filter machine had to switch to standby or off mode within 5 min of the last brew cycle if it stored the coffee in an insulated jug.8 With a non-insulated jug, the limit was 40 min.8 After descaling or self-cleaning, it was 30 min.8 Other household coffee machines had a 30 min limit after brewing.8 According to the European Commission, lifting the pot does not restart the 40 min.9\n\nRegulation 801/2013 amended Regulation 1275/2008, which Regulation (EU) 2023/826 repealed with effect from 9 May 2025.8,10 The 2023 regulation, which applies from that date, keeps the same delays: at most 5 min for drip filter machines with an insulated jug, 40 min with a non-insulated jug and 30 min for other household coffee machines.10 The delay is measured from the end of the last brew cycle or, where applicable, of a descaling or self-cleaning process.10\n\n**What holding costs.** A 2009 life cycle assessment named the time the coffee is kept warm, and the number of cups made per machine and day, as the two key factors for drip filter coffee.11 It assumed 0.125 kWh per litre for heating and 0.001 kWh per minute on stand-by, from its own measurements, with 2 h of stand-by a day.11 Of the three options it compared, drip filter coffee was the most energy-intensive.11 How brewing fits into the footprint of a cup is covered in the carbon footprint entry.\n\n
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Brew time measured for one filter machine6, heated holding specified in SCA 310-20211 and the latest automatic switch-off under EU Regulation 801/2013, unchanged in Regulation (EU) 2023/826.8,10 The first row counts from the start of brewing, the others from the end of the last brew cycle.
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\n\n## Reference values\n\n| Parameter | Value | Basis | Source |\n|---|---|---|---|\n| Slurry temperature | 90–96 °C from 33% of the water sprayed to the end of the cycle | SCA 310-2021, certification test | SCA1 |\n| Brew strength | 1.15–1.55% TDS | At 55 g coffee per 1.000 kg water, full capacity | SCA1 |\n| Extraction uniformity rating | ≥60 on a 0–100 scale | Full capacity, three replicates | SCA1 |\n| Test water | 17 ± 3 °C; calcium hardness 50–175 ppm, alkalinity 40–70 ppm as CaCO₃, pH 6–8 | As stated in SCA 310-2021 | SCA1 |\n| Test coffee | 100% arabica, roast colour #55–#65, rested ≥1–1.5 weeks | SCA roast colour tiles | SCA1 |\n| Heated holding | 80–85 °C for the first 30 min; never above 85 °C from heating | Heated jug only | SCA1 |\n| Brew time limit | None set | SCA 310-2021 | SCA1 |\n| Switch-off, insulated jug | ≤5 min after the last brew cycle | EU household machines, from 1 Jan 2015; kept from 9 May 2025 | Reg. 801/20138; Reg. 2023/82610 |\n| Switch-off, non-insulated jug | ≤40 min after the last brew cycle | As above | Reg. 801/20138; Reg. 2023/82610 |\n| One filter machine | 100 g coffee, 1,800 mL brew, ≈90 °C, 348 s; 1.03% total solids, 19% yield | One recipe, paper filter | Gloess et al.6 |\n| Cafestol, paper-filtered drip | 12 mg/L (4–24), median | Five home brews, two filter types | Orrje et al.7 |\n\n**Grind for the test.** For conical baskets, SCA 310-2021 requires less than 12% (by mass) above 850 µm, at least 68% between 425 and 850 µm and 20% or less below 425 µm.1 For flat baskets: less than 17% above 1,168 µm, at least 65% between 589 and 1,168 µm and 18% or less below 589 µm.1 The standard’s text gives the upper limit of the middle fraction as 1,198 µm, its table as 1,168 µm; we follow the table.1\n\n## History in brief\n\nThe paper filter came first. Melitta Bentz of Dresden registered a coffee filter as a utility model with the Imperial Patent Office on 20 June 1908.12 The earliest patent consulted for this entry that describes the steam-lift pump of a drip machine was filed in 1975.3 No patent or register naming the first electric drip machine was consulted, so no date is given. The history of brewing devices is covered in the history of brewing entry.\n\n## Open questions\n\n- **Holding and flavour.** No study consulted for this entry measured how drip coffee changes in flavour or chemistry on a heated plate or in an insulated jug over time.\n- **Machines on sale.** No peer-reviewed survey of slurry temperature, brew time or extraction uniformity across household machines was found. SCA 310-2021 sets the test but publishes no measurements.1\n- **Metal filters in drip machines.** Cafestol in drip coffee brewed through a permanent metal filter was not measured in the sources consulted. Workplace machines with metal filters were much higher than paper-filtered brews.7\n## Key studies\n\n
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Gloess et al., 2013 – Nine methods side by side. Brews one coffee by nine methods, including a filter machine with a paper filter, and records dose, volume, temperature and time for each. The filter machine gave the lowest total solids and the least caffeine per sip, with a weak but well-balanced flavour.

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European Food Research and Technology 236, 607–627 · doi:10.1007/s00217-013-1917-x

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Orrje et al., 2025 – Diterpenes by brew method. Measures cafestol and kahweol in workplace machine coffee and in home brews, including drip coffee made with normal and perforated paper filters. Paper-filtered drip coffee was low, and the two filter types did not differ significantly; workplace machines brewing through metal filters were mostly much higher.

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Nutrition, Metabolism and Cardiovascular Diseases 35, 103933 · doi:10.1016/j.numecd.2025.103933

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Humbert et al., 2009 – Soluble, capsule and filter coffee. A life cycle assessment of a 1 dl cup made three ways. Drip filter coffee came out as the most energy-intensive option; keep-warm time and the number of cups per machine and day were its key parameters.

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Journal of Cleaner Production 17(15), 1351–1358 · doi:10.1016/j.jclepro.2009.04.011

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