The chlorine odor of tap water can be traced to the chlorine "residual," a low level of chlorine maintained in water to guard against bacteria, viruses, and parasites, which may be in water as it flows from the source to points of use. In the US, even treatment plants that use non-chlorine disinfection technologies are required to add chlorine to the water before it flows into the distribution system. The chlorine residual acts like a "body guard" for water in transit. As long as there is a residual level of chlorine, the consumer is reasonably protected from harmful microorganisms.
To eliminate chlorine, add lemon juice or allow an open container of water to sit for several hours.