Water will give you only a temporary solution to dry hacking cough. It is recommended to see an ENT (Ear, Nose & Throat) specialist. The ENT will prescribe you either anti-biotics or nasal sprays. The cough may get eliminated within a week or so. If you are suffering from sinus, it may take a longer while. You may also have to take sinus medication to prevent the cold and cough. If the pain does not decrease, it is also advisable to take oral steroids. If you still suffer from the problem, get a CT scan done at your nearest hospital. This will enable you to know the cause of your dry hacking cough. It is also wise to take hot steams or saunas. You should also try sweating it out in the gym.