there will not form a chemical bond between water and THC. But THC does dissolve in water in very moderate amounts (2g per litre at 20°C). It dissolves a lot better in non-polar solvents however since it is itself non-polar. similia similibus solvuntur (like dissolves like). so it's probably the smartest to keep using water in your bong which is very polar. if you add some salt it will be even more polar. by the way, you should have googled this question!