Okay, let's get straight to the answer,the firm answer is no, you cannot use water as a contact solution. Using tap water, bottled or even distilled water is never the substitute for contact lens solution.
Tap water is not salty like tears are so contact lenses absorb the water and swell. They hold onto it and this causes a problem. It is not sterile and contains microorganisms. If your lens wells, it changes how the actual contact lens fits on your eye and it will will often times make it tight on the eye. You can also create microscopic breaks in your cornea that microorganisms can get into, which can create infections.
Another common question that is asked by contact wearers is "Can you put contact in water overnight?" When you don’t have contact solution with you, a common technique is to just use water or your own saliva as "emergency" solution.
This is a very bad idea because you are exposing your contact lenses to water or saliva, which are both riddled with bacteria. Putting contacts into your mouth, especially, is like “putting them in a petri dish."
If you don’t have a solution and catch yourself in a situation where your contact lenses are bothering you, it is best to just throw away your contacts. Another option is to use lubricating drops made for use with contact lenses to try to relieve the discomfort. In addition, it is always wise to carry some emergency solution and a contact lens case with you at all times.
It is best to never have your contacts lenses come into contact with water. Not even for one night. When you shower or plan on swimming or using a hot tub, it is better to be safe than sorry and remove them before you get into any type of water. Water carries bacteria and other organisms that can contaminate the lenses and cause serious infections.