Rinse 4 cups fresh or frozen cranberries
Add cranberries and 4 cups water to a pot
Bring to a boil over medium-high heat
Reduce heat and simmer for 10 to 15 minutes
Stir and mash the cranberries as they soften
Remove from heat and let cool slightly
Strain the mixture through a fine mesh sieve or cheesecloth
Press the pulp to extract as much juice as possible
Sweeten with sugar, honey, or maple syrup if desired
Add more water if you want a lighter juice
Chill before serving
Store in a sealed container in the refrigerator