Scrub lemons thoroughly, rinse well, and pat dry. Using a vegetable peeler, carefully strip the yellow rind from the lemons, avoiding the bitter white pith, to measure about 1 cup of peel strips.
Cut a 1/4-inch slice from each end of the peeled lemons. Stand each lemon flat-end down and remove the remaining white pith in strips, cutting from top to bottom following the curve of the fruit.
Coarsely chop the peeled lemons, reserving all juice, to measure about 2 to 2 1/2 cups total.
Combine lemon peel strips, chopped lemon with juice, and water in a 4-quart stainless steel or enameled pot. Bring to a boil, reduce heat, cover, and simmer for 15 minutes.
Line a large wire-mesh strainer with 3 layers of dampened cheesecloth and place over a large bowl. Pour the lemon mixture into the strainer and let drain for at least 3 hours or overnight. You should get about 2 cups of juice. Measure, and adjust your sugar accordingly. You should add 1 cup sugar to every one cup of strained juice. Discard solids.
Combine lemon juice and pectin in a 4-quart pot. Bring to a full rolling boil over high heat, stirring constantly. Add sugar (1:1 ratio to measured juice), stirring to dissolve. Return to a full rolling boil and boil hard for 1 minute, stirring constantly. Remove from heat and skim foam if necessary.
Ladle hot jelly into prepared jars, leaving 1/4 inch headspace. Wipe rims, center lids on jars, and apply bands to fingertip tight.
Process half pints or quarter pints in a boiling water bath canner for 10 minutes, adjusting for altitude. Turn off heat and let jars stand in canner for 5 minutes before removing.