Add water, sugar, strawberries, and rhubarb to a small sauce pan. Bring to a boil over medium-high heat and stir to dissolve the sugar. Lower heat to a simmer and continue simmering for about 10 minutes or until strawberries and rhubarb can be easily mashed. Set aside to cool slightly.
Add syrup mixture to a blender and pulse until smooth, then strain out any remaining seeds or chunks.