Originating from Southeast Asia, water chestnuts are actually roots of an aquatic plant that grows in freshwater ponds, marshes, lakes, and in slow-moving rivers and streams. These roots are commonly grown in Japan, Taiwan, China, Thailand, and sometimes in Australia. Water chestnut harvesting is laborious, making them somewhat expensive to purchase. Processed and canned water chestnuts are widely found in most supermarkets. Fresh water chestnuts are more difficult to find, but are becoming more available.
If you find fresh water chestnuts, select those that are firm with no signs of wrinkling. These will need to be peeled prior to eating and cooking. Fresh tubers may be stored wrapped tightly in a plastic bag for up to one week.
Canned, unopened water chestnuts will store indefinitely. Once opened, they keep up to one week in a bowl of water. Be sure to change the water daily for the "freshest" product.