A lot of ferrets like to dig in their food or water bowls.  If the
bowls are in contained areas and the ferrets are willing to eat off
the floor, the easiest solution is to provide a back-up water bottle
and ignore the digging.  You can also put the bowls in larger pans to
contain the mess; use separate pans for the food and water, so the
spilled food doesn't get soggy and spoil.

Heavy bowls that angle inward can help, or for more diligent
water-bowl diggers, you can switch to a bottle.  Likewise, some people
find that a J-type rabbit feeder works well for food, though others
find that just gives their ferrets a lot more food to joyfully spread
around the room.  At least one person used a PVC p-trap with a smaller
opening instead.  Another nearly dig-proof design is to put the food
in a covered plastic Tupperware-type container and cut a hole in the
top just big enough for the ferret's head.

Some parts © 2009 Advameg, Inc.