Start by washing the concord grapes thoroughly and removing any stems.

In a large pot, combine the grapes and water.

Bring the pot to a gentle boil over medium heat.

Once boiling, reduce the heat and use a wooden spoon to mash the grapes gently.

After about 20 minutes of simmering, remove the pot from the heat.

Pour the mixture through a strainer or cheesecloth to separate the juice from the solids.

Return the strained juice to the pot and add sugar to taste.

Stir until the sugar dissolves completely.

If using, stir in the lemon juice.

Let the juice cool before pouring it into glass jars or bottles.

Store it in the refrigerator for up to a week.