1. Your water isn’t the right temperature
If the water is too hot, you can scald your coffee and make it bitter, and if it’s too low, the flavors will be dull. The water should be around 205 degrees Fahrenheit, or just off boiling (boiling water is 212 degrees Fahrenheit). Boiling water extracts the bitter elements from the coffee and makes coffee taste bitter and acidic. Temperatures below 200 degrees on the other end are too low and unable to activate the compounds that produce the wonderful coffee aroma and flavor. The sweet spot is 200 to 205 degrees. However, Cold Brew coffee does not need any heat.