Porcelain can be cleaned regularly with a mild cleanser, warm water and a clean soft cloth or sponge. Simple oversights such as letting soap or toothpaste dry on the sink can stain the finish.
To sanitize porcelain a mild chlorine-bleach cleaner such as Soft Scrub® can be used. Rinse immediately after use and dry. Be sure to follow the manufacturer's instructions. Another option is to let the sink soak in a bleach solution (approximately one part bleach/three parts water) for thirty minutes to an hour; then drain, rinse well, and dry.