To make the simple syrup, place the 2 cups water, sugar and rhubarb in a large saucepan and bring to a boil. Stir to dissolve sugar. Once dissolved, remove from heat and allow to cool to room temperature. If you want it to chill a little quicker, you can stick it in the fridge.
Once the simple syrup is cool or at least room temperature, place it in a large pitcher, add the lemon juice and water.
Pour over ice and serve.
Recipe by Foods of Our Lives at https://www.foodsofourlives.com/2013/07/homemade-rhubarb-lemonade/