Bread and milk is no alternative for fresh meat. Tinned cat food also has this effect. A smelly cage will attract all manner of small insects and flies and may even cause illness. A drinking bottle or a stainless steel bowl set in cast concrete collar, to stop the ferrets tipping it over, are ideal. Some ferrets will love to put their heads in the water and splash it everywhere if they are given the chance so you may need a rod across the bowl.
Cleanliness is all important.
Do not bath too often or you will destroy the natural oils in your ferrets' coat. On the other hand if you come in from a day's working and your ferret is filthy it may be a good time for a bath, so you can check for ticks or injuries. Caring for your ferret requires regular scrupulous checking of its well being. Clear surplus wax from the outer ears and apply an ear wash, idealy when you clip the claws. Be aware of cuts, abrasions and bald patches.