Can scabies be treated using salt water?

No: The scabies mites live under the skin and don't care what kind of water you put on them. To treat scabies, you need medication.

Scabies: Scabicides kill scabies mites and sometimes the eggs. These generally require a doctor’s prescription. No otc products have been tested and approved to treat scabies, but you can try anything. Salt is not likely to hurt you but not using approved drugs may prolong the illness.