In general, not unless you want to change your tap water's taste or remove the minerals that cause it to be hard. While many people prefer the taste of bottled water, tap water is subject to even more-stringent quality standards than bottled water and is tested more frequently.
Some customers may be sensitive to the taste or odor of their tap water caused either by naturally occurring minerals or by residual chlorine added to ensure disinfection. We recommend first trying the simple practice of placing the water in a pitcher and letting cool in the refrigerator. Also, most inexpensive carbon filters will remove residual chlorine.
Pregnant women and people with medical conditions affecting their immune system should consult a physician to determine whether a supplemental treatment system is appropriate.