Cut watermelon into medium sized chunks. Transfer in batches to blender and puree with ginger.
Pour liquid from blender to a pitcher through a fine mesh strainer to remove some of the pulp. Serve over ice.
The juice is good and refreshing as is, but you can also add some soda water to add a little fizz to it. The ratio that we found worked well was ¾ juice to ¼ soda water, but it's really a personal preference.
Recipe by Things I Made Today at https://www.thingsimadetoday.com/2013/07/07/watermelon-ginger-juice/