This is what NSW Health are telling us: (and we are having a very low rate of infection and death here)
"According to the World Health Organization, it is not certain how long the virus that causes COVID-19 survives on surfaces, but it seems to behave like other coronaviruses. Studies suggest that coronaviruses (including preliminary information on the COVID-19 virus) may persist on surfaces for a few hours or up to several days. This may vary under different conditions (e.g. type of surface, temperature or humidity of the environment).
If you think a surface may be infected, clean it with a common household disinfectant to kill the virus and protect yourself and others. Clean your hands with an alcohol-based hand rub or wash them with soap and water. Avoid touching your eyes, mouth, or nose."
In other words, don't become paranoid about this, just clean surfaces with a disinfectant and wash your hands regularly.