In small sauce pan, combine the rhubarb, sugar, water, lemon juice, and salt. Heat on medium and cook for 5 minutes. Stir occasionally. When the rhubarb turns smooshy, remove from heat.
Pass the contents of the pot through a strainer. Let cool.
Stir the rhubarb syrup into the seltzer.
Recipe Notes
Notes:
The syrup can be stored for 2 days in the refrigerator.