n a blender add the water, can of sweetened condensed milk and 1 whole lime. Blend until completely smooth. Strain the mixture into a juice pitcher and throw away the excess pieces of the lime.
To this mixture, add the zest and juice of the remaining four limes. Add the ice and stir. Serve immediately. If you like a stronger lime flavor but you don't want to use more limes you can add one packet of True Lime Powder that you can buy in the grocery store near the drink aisle.