1 large airtight glass container or Mason jars (4 pint-sized Mason jars work perfectly)
1 sharp knife or peeler
1 double-layer of cheesecloth
2 glass containers with airtight lids, such as Mason jars
Peel grapefruits and lemons and slice into smaller sections. In 4 pint-sized Mason jars, or 1 large Mason jar or some other large, airtight glass container, combine citrus peels with herbs and spices. Cover citrus peel and herb/spice mixture with grain alcohol until all ingredients are submerged. Apply lid to container and give mixture a shake. Set the glass jars in a cool, dark place for 3 weeks, giving the mixture a good shake at least once a day.
After 3 weeks, cover a glass container with cheesecloth and secure with a rubber band or piece of string. Pour bitters mixture through the cheesecloth, collecting the citrus peels, herbs and bitters in the cloth. Gather the ends of the cheesecloth and tie them together so that the citrus peels, herbs and spices are completely enclosed. Steep cheesecloth in 8 ounces water until water is at room temperature. Discard the solids and add the steeped water to the glass container of infused alcohol mixture. Seal with a lid and give it a shake.
Let the water and alcohol mixture sit in a dark place for 5 days, giving the mixture a shake each day. After 5 days, strain bitters through a double layer of cheesecloth. If still cloudy, strain again through some coffee filters until clear. Transfer bitters into small tincture bottles with droppers.
Store bitters in a cool, dark place.
NOTE: When first experimenting with bitters, try 1 to 3 droppers full of bitters per beverage or to taste. Grapefruit bitters can be refrigerated in an airtight container for up to 1 month.