Yes, you shall not wash your contact lenses with tap water. Tap water usually contain some bacterial that we can't see. Your contact lenses my get the bacterial in tap water. However, unlike eyeglasses, contact lenses can directly contact our eyes, it is likely cause eye infection if there is bacterial on the contact lenses. This is the reason why contact lenses are required to to be clean with contact solution. So, you shall buy a bottle of contact lenses solution when you buy contacts for the sake of your eyes. Even if you don't wear your contact lenses, you still require to wash your contact lenses with contact solution at least 3 days a time.
Yea, tap water is very bad for contacts, never use tap water to wash your contacts. Otherwise, you are likely to suffer from a serious eye infection because tap water is not sterile and it contains plenty of bacteria or protozoa that can cause serious damage to your eyes. Do not take chances. Washing your contacts with water can increase your risk of feeling discomfort and suffering from eye infections. Rub your contact lenses with contact lens solution and after each use of the solution, you should empty and refill your lens case with fresh contact lens solution. Eyes are the window of the soul, protect them.
There are plenty of contagious microorganism which can be extremely harmful to the eyes if you wear the eye contact lenses washed by the tap water. For example, there are acanthamoeba bacteria in the tap water, and they can cause the keratitis. Therefore, the eye contacts should be completely away from the tap water. As to the cleaning of the eye contacts, you should use professional care solution to wash clean the contacts. And the care solution should also be used to store the contacts in clean container. Remember to change the care solution in the container every day, and do not repeat using it or mix the old with the new solution.