SINCE THE PHONE IS WITH you 24x7 they stand the highest risk of getting wet. Even if you are using a good cover to protect it from dust and scratches, it won't be good enough to stop the water from getting in. All smartphones have multiple ports through which water can seep in and damage the circuit board. You can get over this problem by buying covers like the Capedase for iPhone that come with plugs for these ports. There are also special covers that protect the phone from water damage, like the Grifiin Survivor Case. Such options are available for all smartphones, though at a cost. Prices start from ` 1,500.