They do drown very easily though so I'd suggest instead of splitting the tank half land-half water get a tall dish or tub with a lip that they can't access or get over. They do great under leaf cover or moss and other moist areas, like if you raised your water dish over some thin pieces of slate and kept it wet in that side of the tank.

A little wet fish food sprinkled here and there near their haunts will keep them fed. I'm with berksmike though, if you want to raise them start another tank.

You don't really need half water/half land for toads anyway!