A couple things.
A lot of the more hooty-tooty Argentines don´t drink cold water directly from the tap, but they do use it for tea, noodles, etc. Coke, sprite, pomelo, whatever, is probably worse for you than the general tap water here, just a heads up for all you fat people in your 40s and 50s (diet included). Again, depending on where you live, there is a different treatment center. The main treatment center (the big one) for the most part uses ozone except for special circumstances.
also, you need to check the tank in your apartment as well, as that could contribute to the mugre. There might be little filers under the faucets with junk (from the tank), which could contribute to lack of water pressure. If water pressure is a personal problem, you could install a pump, its not too expensive.
Also, try to pin point what exactly you are afraid of. Boiling water won´t help with the free chlorine and the filters won´t exactly help with the bichos.
And what is your reasoning for trusting the bottled water?