A clogged sink is always a nuisance, but a sink clogged with rice can often be a more severe problem because ordinary household and chemical cleaners do not always break down the rice and remove the blockage. Because of the potential risks associated with this problem, avoid pouring rice down the sink whenever possible. However, you can treat a sink that has been clogged with rice using over-the-counter or homemade solutions.

...
Rice can clog sinks and potentially damage plumbing in your home.

Symptoms

Some signs that your sink is clogged with rice is if the sink takes a long time to empty after being filled -- if it empties completely at all -- which will cause water to sit in the sink, along with any other food products or chemicals that have also been used. If your sink has a garbage disposal, use that as your first defense of getting rid of any rice stuck in the drain.

All Natural Remedies

Use some homemade cleaning solutions to help push the rice out of the sink. While this may be bad for your pipes if done excessively, boiling hot water can be a powerful declogger. This option works especially well at powering out gross amounts, which could be holding your rice inside the drain. Boiling water can push out the rice if it is lodged to the inside of your piping.

Another combination is baking soda and water. One part baking soda to every three parts hot water can be a powerful declogging agent. You can also try pouring vinegar along with the baking soda, letting the agents sit for several hours and then flushing through with boiling water.

Drain Piping

If the piping beneath the sink is easily accessible, place a bucket underneath the pipes to collect water. Unscrew the fastener around the drainpipe. Allow the contents of the drain to empty into the bucket. Flush out the pipes with hot water to push the rice out into the bucket. Replace the drainpipe once it is emptied.

Snaking

If the homemade solutions don't work, commercial declogging agents might be your best bet. Because the rice is likely lodged along the sides of your piping, "snaking the drain" will likely be more effective than simply pouring chemicals into the drain, which involves inserting a type of hook into the drain and pulling out the offending clog, which is sometimes hair or food. Once this clog is removed, the rice can move more down the drain.

Prevention

One of the best ways to prevent a clogged sink is to discard of rice in a trash can or compost bin. If you do not have a garbage disposal, a thin-netted drain filter will help catch the rise before it begins to clog your drain.