Rinse the rice in a sieve under running water, then dump into the slow cooker. Add the salt and 5 cups (1.2 L) water. Cover and cook on low for 3 to 4 hours, until tender, checking it occasionally to make sure it doesn’t overcook. Drain in a sieve and rinse under running water to cool. Store covered in the refrigerator for up to 5 days or in the freezer for up to 6 months.