Scrub the lemons well and cut into halves. Place into a large heat resistant pitcher. Add the sugar.
Bring the water to a boil in a saucepan. Pour it over the lemons, stirring to dissolve the sugar. Cool for 20 minutes. Squeeze the juice from the lemons into the pitcher and discard the lemons. Strain the lemonade into another pitcher and chill until serving time.
Serve over ice in tall glasses with a garnish of mint. Add a dash of grenadine for pink lemonade.