Put the fruit in a preserving pan or a large, heavy-based saucepan. Add the water and simmer, mashing and stirring from time to time, for 30 minutes, or until softened. Add the sugar and stir over low heat until dissolved completely. Bring to a full rolling boil and boil for 20–30 minutes, then test for a set. If setting point has not been reached, boil for 5 minutes more, then test again. Pot and cover immediately.