You can boil or evaporate the water and the salt will be left behind as a solid. If you want to collect the water, you can use distillation. One way to do this at home would be to boil the saltwater in a pot with a lid. Offset the lid slightly so that the water that condenses on the inside of the lid will run down the side to be collected in a separate container. Congratulations! You've just made distilled water. When all of the water has boiled off, the salt will remain in the pot. Evaporation works the same way, just at a slower rate.