Coffee Maker Buying Guide: What to Know Before You Buy

The Specialty Coffee Association (SCA) recommends a brew ratio of 1:16 by weight, one gram of coffee per 16 grams of water. For households without a kitchen scale: the standard tablespoon approximation is 1 to 2 tablespoons of coffee per 6-ounce cup of water (the measurement size used on most coffee maker carafes). At 1 tablespoon per 6-ounce cup: weak extraction suitable for mild coffee drinkers. At 2 tablespoons per 6-ounce cup: stronger, fuller extraction suitable for most coffee drinkers. Adjusting the ratio is the simplest way to change coffee strength without adjusting any machine settings, stronger ratio produces more concentrated, full-flavored coffee; weaker ratio produces lighter, more dilute coffee. Most people who compla in that their coffee maker produces weak coffee are using too little coffee for the water quantity, not that the machine is defective.

Deep cleaning schedule: descale every 1 to 3 months (monthly in hard water areas; every 3 months in soft water areas). Mineral buildup (scale) in the water reservoir and heating element reduces brew temperature and slows water flow through the system, both degrade coffee quality. Descaling method: fill the reservoir with equal parts white vinegar and water, run a brew cycle, discard the carafe contents, then run 2 to 3 cycles of fresh water to rinse. Some machines have a dedicated descale mode. Daily maintenance: rinse the carafe and filter basket after each use. Remove and wash the carafe with dish soap weekly. Leaving brewed coffee residue in the carafe or basket accelerates oil buildup that produces rancid-tasting coffee. The single most common reason coffee tastes bad in a machine that once made good coffee: infrequent cleaning and scale buildup.

Medium grind is the standard for drip coffee makers, approximately the consistency of coarse sand. A medium grind balances extraction rate with contact time in a drip machine: the water contacts the grounds for 4 to 8 minutes at 195 to 205 degrees, and a medium grind extracts properly in that contact time. Too fine a grind (espresso grind): over-extraction and bitterness, and grounds may pass through the filter into the carafe. Too coarse a grind (French press grind): under-extraction and weak, sour coffee. For cone-filter machines: slightly finer than medium works better because the narrower filter cone has longer ground contact time. For flat-bottom filter machines: medium to medium-coarse works better because the wider, shallower grounds bed extracts faster. When buying pre-ground coffee: look for 'drip' or 'medium' grind on the package.

Pre-infusion (also called bloom) is a brief pre-wetting of the coffee grounds with a small amount of hot water before the full brew cycle begins. When hot water first contacts freshly roasted coffee grounds: the grounds release CO2 gas (degassing), which, if not released before full extraction, creates uneven extraction by preventing water from penetrating the grounds evenly. Pre-infusion gives the CO2 approximately 30 to 45 seconds to degas before full water flow begins, producing more even extraction and fuller flavor. In practice: pre-infusion is most noticeable with fresh-roasted coffee (with in 2 to 4 weeks of roast date). With older or grocery-store coffee that has already off-gassed: pre-infusion has minimal effect. Machines with dedicated pre-infusion modes: Breville Precision Brewer (bloom mode), Bonavita BV1901TS (pre-infusion), and most SCA-certified machines. Standard budget machines do not have pre-infusion.