White vinegar and ice are used for the toilets... I'm not sure what is used in the galley drains,
We have a product called AES that we pour down the drains. It is some sort of biological cleaner that is meant to break down the gunge that grows in the drains. It seems to work, but don't know how well. It takes its time so we pour it down at night and leave it. Seems to do the trick.