Different waters taste differently. Tap water taste differs from region to region. Bottled water tastes differently between brands and also compared to tap water. This is also caused by varying amounts of minerals.

If you think your sense of taste works fine, but can not tell taste differences in water, try making direct comparisons. Take some bottled water and some tap water (if it is safe for drinking whereever you live). Then take a sip, focus on the taste. Try making out differences. Repeat a couple of times.
If you still can’t make out any differences and you weren’t impatient, it might be worth training your sense of taste first, because water does have a flavour.