Preheat oven to 450°F Dry pork roast as much as possible with a paper towel.
Using a sharp knife, cut halfway through the fat layer (but not the meat) in horizontal lines 1/2" apart. Then make vertical lines 1/2" apart, making a cross-hatch pattern.
In a small bowl, combine the salt, cloves, mustard seeds, and crumbled bay leaves. Rub the mixture into the pork roast, making sure to work it into the fat layer.
Place in a deep roasting pan and roast for about 30 minutes or until top is crackling and golden brown. Reduce heat to 350°F and carefully pour the water into the pan.
Cook another hour, or until meat reaches 160°F.
Remove crackling from roast, cut roast into slices, and serve crackling with the roast.