Does washing kimchi with water reduce the sodium content much?
Answer depends on how the kim chi is made.

I make it using a variant on this recipe.
The protocol there is to treat the leaves with a salty brine for 4 hours, then rinse them extensively.

No further salt is added in the recipe, so any salt in the final product will have osmosed into the leaves. Most of that salt won't come back out except with a prolonged soak*.

I've seen other kim chi recipes that do involve adding back salt after the initial brining and rinse. The sodium content of those could be reduced with a quick rinse, but you'll likely lose flavor too.




Juices in with the kim chi are likely at euilibrium with sodium in the leaves, so simply pressing the stuff lightly to remove as much juice as possible might be the best way to limit sodium without sacrificing too much flavor.