why does city tap water taste sweet?!

Lol I'm glad your tap water tastes sweet... Ours tastes like chlorine and smells like s**t. Seriously.

but the taste is probably from all the processing it has to go through to make it drinkable. Oh, and if you wanna try and change the taste, boil it and then stick it in your own bottles. We've done that here when we ran out of bottled water faster than we thought we would

Water contains various chemical compounds, including many trace minerals. The quantity and quality of these elements give water its taste. Calcium, for example, makes water sweet.

Read more: http://wiki.answers.com/Q/What_makes_pur…

The quality of water depends on where you live. You may also find that your water pipes may have grime inside them if not checked regularly.

its contaminated with piss and dead fish

That might depend where you live