Water quality also plays a massive role in the way your coffee tastes. As we discovered in our review of the best water filters, water isn’t tasteless. Total dissolved solids (TDS) are what give “good tasting” water its sweetness — in fact, the SCAA recommends water with 150 milligrams per liter of TDS to brew coffee. (Want to check your water? A TDS reader is only about 15 bucks.)
It’s not that cone filters won’t make a great cup of coffee — the OXO On 9-Cup still ranked fifth out of 10 in our taste test. But flat bottoms generally allow for the grounds to be more evenly extracted and increase the coffee’s flavor. (It’s no coincidence our other three recommendations have flat-bottom brew baskets). You may have to do a little more tweaking to get this coffee maker’s brew to the best it can be, and that’s the other reason we like the 12-cupper more. This smaller version doesn’t let you tinker with water temperature.
Bunn-O-Matic came out with a different drip-brew machine. In this type of coffeemaker, the machine uses a holding tank or boiler pre-filled with water. When the machine is turned on, all of the water in the holding tank is brought to near boiling point (approximately 200–207 °F or 93–97 °C) using a thermostatically-controlled heating element. When water is poured into a top-mounted tray, it descends into a funnel and tube which delivers the cold water to the bottom of the boiler. The less-dense hot water in the boiler is displaced out of the tank and into a tube leading to the spray head, where it drips into a brew basket containing the ground coffee. The pourover, water displacement method of coffeemaking tends to produce brewed coffee at a much faster rate than standard drip designs. Its primary disadvantage is increased electricity consumption in order to preheat the water in the boiler. Additionally, the water displacement method is most efficient when used to brew coffee at the machine's maximum or near-maximum capacity, as typically found in restaurant or office usage. In 1963, Bunn introduced the first automatic coffee brewer, which connected to a waterline for an automatic water feed.
For many of us, the daily grind can't begin until we've had that first cup of piping hot coffee—so the right brewer is at the top of the list. The most basic coffee makers make at least a decent cup, but a little more money buys conveniences such as programmability, a thermal carafe to keep coffee hot longer, settings that let you adjust brew strength, and more.