Cook rhubarb and water until tender,add sugar and lemon juice and stir together well. Cook over medium-high heat for 10 minutes or until you reach a boil that can not be stirred down. Add Jello and stir until dissolved. Bring to a boil for 2 minutes. Fill sterilized hot jars to 1/4 inch from rim of jars. Remove bubbles, wipe jar rims with hot damp cloth. Seal in jars to fingertip tight. Put in boiling bath canner with lid on for 15 minutes. Remove lid from canner, let sit 5 minutes. Remove jars from canner to a towel lined counter to sit and cool for 24 hours before storing.
**** if you need a little water, don't be afraid to add it whild cooking down the rhubarb... but go sparingly as the rhubarb creates liquid..