If you have a high-powered blender, like a Vitamix or Blendtec, you probably won't need to strain your watermelon puree. If you have a less powerful blender, the puree with be thicker. It's still perfectly delicious, but if you prefer a thiner drink you can strain it through a mesh sieve to remove the pulp. I also really like to make frozen lemonade with this recipe. Leave out the sparkling water and blend the more concentrated lemonade with a pitcher full of ice.