Wash and chop 6 fresh limes into about 8 pieces each.

In a blender, combine lime pieces, 3 cups of cold water, and 1 cup of sweetened condensed milk. Blend on high for about 30 seconds.

Place a fine mesh strainer over a large pitcher or bowl and pour the lime mixture through it, using a spatula to press down on the pulp.

Fill 2 cups with ice and pour the filtered mixture over the ice.