With most household electric coffee makers, the user often only has six variables they can adjust to improve the coffee: 1) the coffee quality; 2) the water quality; 3) the coffee roast level; 4) the coffee grind size; 5) the amount of coffee and water being used, which is called the brew ratio; and 6) the type of coffee filter being used. Once you learn the significance of each of these variables, you can adjust them to work in harmony with one another to brew fantastic coffee repeatedly.
Coffee and water quality: Since water and coffee are the two ingredients in brewed coffee, it should not come as a surprise that the quality of these two ingredients largely determines the outcome. Your cup of coffee will never exceed the quality of the water and coffee used. High quality coffee with low quality water will result in less than optimal results. Low quality coffee with low quality water will always result in low quality brewed coffee. Use reasonably fresh coffee ground at the time brewing for optimal results. We have other posts on our website about this topic under the learn tab.
Roast level: Since most household electric drip coffee makers do not allow the user to control the brewing temperature, it is extremely important to select a coffee roast level that is compatible with the brewing temperature of your brewer. As a general rule, there is a correlation between roast level and optimal brewing temperatures with lighter roasted coffees doing better with hotter water temperatures and darker roasted coffees doing better with cooler water temperatures. Lighter roasted coffees are the least water soluble and need higher brewing temperatures in the range of 200-210F. Medium roasted coffees generally brew well in the 200-205F range. Darker roasted coffees are the most water soluble and do well with lower water temperatures in the range of 195-200F. Many cheap household drip coffee makers brew at lower water temperatures and are not temperature stable. Do yourself a favor and take your brewer’s temperature. Run a cycle of water through the brewer and place a meat thermometer under the water flow for the entire brew cycle to see what temperature your brewer reaches and whether it maintains that temperature for the entire brewing cycle. Most lower cost household drip coffee makers are best suited for medium to darker roasted coffees. While we love lighter roasted coffees and believe they offer the most unique flavor experience when it comes to coffee, most household drip coffee makers do not brew at adequate water temperatures to brew them well.
Grind size: The only way to consistently be able to replicate grind size is with a burr grinder with definitive grind adjustments. Adjusting the grind size of coffee makes a coffee more or less soluble. The finer a coffee is ground the more surface area is exposed to water increasing solubility. The coarser a coffee is ground the less surface area is exposed to water decreasing solubility. Adjusting the grind size also regulates the flow of water through the bed of coffee. A coarser grind size will result in a faster flow rate and brew time. A finer grind size will slow the flow rate down and extend the brew time. Combine these two principles and you get a better idea how to adjust the flavors your tasting. If your coffee tastes weak or sour, grind finer. This will slow the water flow and increase the level of extraction. If your coffee tastes bitter, harsh, or just too strong, grind coarser. This will increase the water flow and lower the extraction. As a general starting point, most drip coffee makers are going to do well with coffee ground with a medium coarseness and most burr grinders provide you recommendations for what grind settings to use for various brew methods.
Brew ratio: All drip coffee makers have an ideal range for how much coffee can be brewed. Consult the manufacture’s recommendations to learn what this range is. One word of caution is to watch the depth of the bed of coffee. General recommendations are not to exceed two inches but this is not a hard and fast rule. The coffee to water ratio you use is at the end of the day preferential in terms of how strong you prefer the coffee. We prefer a 1:15 ratio (e.g., 1 gram of coffee to 15 grams of water), which is on the stronger end. Many prefer a 1:17 ratio. You can also use your brew ratio to assist with fine tuning the extraction. By increasing the amount of water brewed through the same amount of coffee, you will increase the extraction. By decreasing the amount of water brewed through the same amount of coffee, you will decrease the extraction. To increase repeatability, we recommend using a digital scale to weigh out your coffee and water amounts.
Filters: Filters influence the flavor of your coffee in three primary ways. First, there is the issue of metal or paper filters. Metal filters allow fine sediment and coffee oils to pass through and into the cup. This results in a very different experience than with paper filters, which results in a cleaner cup of coffee. Second, some paper filters impart undesirable flavors to your cup of coffee. This is why it is common advice to place your paper filter in the brewing basket and rinse it with tap water. It does not have to be hot water. If you are curious about this, taste the water after rinsing the filter. Bleached filters produce less flavors than natural brown filters, but they are all different. Third, paper filters are all different when it comes to flow rate. Some are designed for slower or faster flow rates. This is important to know if for no other reason than you may one day you buy a new brand of coffee filter and all of sudden discover your coffee tastes different. If so, you may have to adjust your grind size to accommodate your new filters.
In summary, if you want to increase your odds of brewing a great cup of coffee: 1) use high quality coffee and water; 2) figure out what temperature your drip coffee maker brews at and select the appropriate roast level; 3) rinse your paper filters; 4) start with a ratio of coffee to water in the range of 1:15 to 1:17 and an amount of coffee that fills around two inches of your brew basket; 5) grind your coffee with a burr grinder to the recommended setting for drip coffee makers just prior to brewing; 6) while you in the learning phase, change one variable at a time so that you understand how the change impacted the flavor your perceive; 7) keep notes for future reference; and 8) have fun. Most roasters will provide you with recommendations for how best to brew their coffee on their website and most would love to interact with you to help you get the best cup of coffee possible.
Coffee tastes bitter (i.e., over-extracted)
Step 1: grind coarser
Step 2: reduce the brew ratio (e.g., use less water)
Step 3: try a lighter roast than current roast level (dark > medium-dark; medium-dark > medium; etc.)
Coffee tastes sour (i.e., under-extracted)
Step 1: grind finer
Step 2: increase the brew ratio (e.g., use more water)
Step 3: try a darker roast than current roast level
Coffee tastes too strong
Step 1: increase the brew ratio
Step 2: grind coarser
Step 3: may be a middle ground of slightly increasing the brew ratio and the grind size
Coffee tastes too weak
Step 1: reduce the brew ratio
Step 2: grind finer
Step 3: may be a middle ground of reducing increasing the brew ratio and the grind size