Bring water to boil in a sauce pan. Place flat lids in boiling water.
Turn off heat. Wash jars and screw bands in hot soapy water;
rinse with warm water. Let stand in hot water until ready to use. Drain well before filling.
Measure juice into 6- or 8-qt. saucepot; add food coloring.
Stir pectin into juice in saucepot. Add butter to reduce foaming. Bring mixture to full rolling boil (a boil that doesn't stop bubbling when stirred) on high heat, stirring constantly. Stir in sugar. Return to full rolling boil and boil exactly 1 min., stirring constantly. Remove from heat. Skim off any foam with metal spoon.
Ladle immediately into prepared jars, filling to within 1/8 inch of tops. Wipe jar rims and threads. Cover with two-piece lids. Screw bands tightly. Turn upside down to seal lids. Let sit for at least 12 hours. Turn upright. Check seals by pressing middles of lids with finger. (If lids spring back, lids are not sealed and refrigeration is necessary.)