In a medium size pan, add the water, sugar, zest and juice. Heat the pan on low to medium heat. Stir while it's cooking; let cook until the sugar is completely dissolved. Add the cranberries and stir.
Cook for another 10 minutes and then turn the heat down to the lowest setting. Cover the pan and let simmer for another 15 to 20 minutes or until the desired thickness is reached. Stir occasionally. The sauce will thicken as it simmers. Remove from the stove and let cool.
Serve chilled or warm.
For recipes where both the zest and the juice of a citrus fruit is needed, make sure to first zest the fruit before cutting and juicing it. It's much easier to zest (scraping or cutting from the outer colorful skin of unwaxed citrus fruits) citrus fruits while the skin is still whole.