Combine strawberries and water in a flat-bottomed kettle; crush berries. Cover and bring to a boil. Reduce heat, and simmer, uncovered, 10 minutes, stirring frequently. Strain berries through a damp jelly bag, reserving 3 3/4 cups juice. Discard pulp.
Combine reserved juice, lemon juice, and sugar in kettle. Bring to a rolling boil, stirring constantly. Add liquid pectin, and return to a boil. Boil 1 minute, stirring constantly. Remove from heat; skim off foam with a metal spoon.
Quickly ladle jelly into hot sterilized jars, leaving 1/4-inch headspace. Cover with metal lids, and screw bands tight. Process in boiling-water bath 5 minutes.