Rinse all calamansi fruits under cool running water and pat dry, discarding any with soft spots.

Roll each calamansi on the counter with gentle pressure for 5 to 10 seconds to release juices.

Cut each calamansi in half crosswise on a cutting board using a sharp knife.

Squeeze each calamansi half firmly over a pitcher or large bowl using a citrus juicer or by hand to extract all juice.

Optional: strain the juice through a fine mesh strainer into a clean pitcher to remove pulp.

Add 4 cups of cold water to the pitcher and stir well to combine.

Add 3 tablespoons of sugar and 1/4 teaspoon of salt, stirring until fully dissolved; taste and add up to 1 more tablespoon sugar if desired.

Chill the juice in the refrigerator or serve immediately over ice.