If your tap water is bad, you may notice a change in its appearance, taste, or smell. It may also cause your skin or hair to feel dry and irritated after contact. If you suspect your tap water is bad, you should contact your local water utility for testing.there are a few ways to tell if your tap water is bad. First, if it has a strange odor, it may be contaminated. Second, if it has a strange taste, it may also be contaminated. Finally, if it is cloudy, it may be contaminated. If you notice any of these signs, you should contact your local water authority to have your water tested.